bims-metlip Biomed News
on Methods and protocols in metabolomics and lipidomics
Issue of 2022–12–11
forty papers selected by
Sofia Costa, Matterworks
  1. Good practices and recommendations for using and benchmarking computational metabolomics metabolite annotation tools.
  2. Shotgun Lipidomics of Rodent Tissues.
  3. CCS Predictor 2.0: An Open-Source Jupyter Notebook Tool for Filtering Out False Positives in Metabolomics.
  4. Integrated Exposomics/Metabolomics for Rapid Exposure and Effect Analyses.
  5. Problems, principles and progress in computational annotation of NMR metabolomics data.
  6. Integrating ion mobility into comprehensive multidimensional metabolomics workflows: critical considerations.
  7. Novel Method for Comprehensive Annotation of Plant Glycosides Based on Untargeted LC-HRMS/MS Metabolomics.
  8. Development and validation of an analytical method using liquid chromatography-tandem mass spectrometry for the therapeutic drug monitoring of seven cardiovascular drugs in clinical usage.
  9. Method validation and clinical application for the quantification of lopinavir, efavirenz, and ritonavir in breast milk using liquid chromatography tandem mass spectrometry.
  10. Decoding Distinct Ganglioside Patterns of Native and Differentiated Mesenchymal Stem Cells by a Novel Glycolipidomics Profiling Strategy.
  11. On the importance of color in mass spectrometry imaging.
  12. Mass Spectrometry Imaging of Lipids Using MALDI Coupled with Plasma-Based Post-Ionization on a Trapped Ion Mobility Mass Spectrometer.
  13. Image classification combined with faster R-CNN for the peak detection of complex components and their metabolites in untargeted LC-HRMS data.
  14. Trace determination of prohibited acrylamide in cosmetic products by vortex-assisted reversed-phase dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry.
  15. Comprehensive Profiling of Phosphomonoester Metabolites in Saccharomyces cerevisiae by the Chemical Isotope Labeling-LC-MS Method.
  16. Chiral LC-MS/MS method for the simultaneous determination of (R,S)-ketamine, (R,S)-norketamine, and (2R,6R;2S,6S)-hydroxynorketamine in mouse plasma and brain.
  17. Analysis of 12 Chemical Compounds And Pattern Recognition of Different Parts of Angelicae Sinensis Radix by Liquid Chromatography-Tandem Mass Spectrometry And Chemometrics Methods.
  18. Rapid, sensitive, and high-throughput quantification of broad serological ceramides by using isotope dilution liquid chromatography-negative ion electrospray tandem mass spectrometry.
  19. A Review on Spike and Recovery Method in Analytical Method Development and Validation.
  20. Metabolite Extraction from RPE Cells and Retinas Related to Retinitis Pigmentosa.
  21. A Validated UHPLC-MS/MS Method for Determination of Nalbuphine in Human Plasma and Application for Pharmacokinetic Study of Patients Undergoing General Anesthesia.
  22. Quantification of Remimazolam Besylate (CNS7056B) and Its Metabolite (CNS7054X) by LC-MS/MS in Human Plasma Using Midazolam-d4 Maleate as Internal Standard.
  23. New challenges in sample preparation: Miniaturized stir bar sorptive dispersive microextraction as a high-throughput and feasible approach for low-availability sample preparation.
  24. Rapid determination of polyethoxylated tallow amine surfactants in human plasma by LC-MSMS.
  25. Different approaches for estimation of the expanded uncertainty of an analytical method developed for determining pharmaceutical active compounds in wastewater using solid-phase extraction and a liquid chromatography coupled with tandem mass spectrometry method.
  26. Validation of an LC-MS/MS method for the determination of sotorasib, a KRASG12C inhibitor, in human plasma.
  27. Analysis of the Amine Submetabolome Using Novel Isotope-Coded Pyrylium Salt Derivatization and LC-MS: Herbs and Cancer Tissues as Cases.
  28. Development and validation of an LC-MS/MS method to quantify kynurenic acid in human plasma.
  29. A rapid and systematic approach for the optimization of radio thin-layer chromatography resolution.
  30. Review on atmospheric pressure ionization sources for gas chromatography-mass spectrometry. Part II: Current applications.
  31. Method development for the acquisition of adsorption isotherm of ion pair reagents Tributylamine and Triethylamine in ion pair chromatography.
  32. Development of two fully automated quick, easy, cheap, effective, rugged, and safe pretreatment methods for the extraction of psychotropic drugs from whole blood samples.
  33. Lipidome variation of industrial Saccharomyces cerevisiae strains analyzed by LC-QTOF/MS-based untargeted lipidomics.
  34. Synthesis of emerging cathinones and validation of a SPE GC-MS method for their simultaneous quantification in blood.
  35. Immunopurification Reagents and Their Application in Biologics and Biomarker Quantitation Using LC-MS/MS in Drug Discovery.
  36. Sweat Cortisol and Cortisone Determination in Healthy Adults: UHPLC-MS/MS Assay Validation and Clinical Application.
  37. A GC-MS/MS method for trace level quantification of six nitrosamines impurities (NDMA, NDEA, NEIPA, NDIPA, NDPA, and NDBA) in commercially used organic solvents: Dichloromethane, Ethyl acetate, Toluene, and o-Xylene.
  38. "Organ-in-a-Column" Coupled On-line with Liquid Chromatography-Mass Spectrometry.
  39. A stable isotope assay with 13C-labeled polyethylene to investigate plastic mineralization mediated by Rhodococcus ruber.
  40. Quantification of Monoamine Neurotransmitter Metabolites and Cofactors in Cerebrospinal Fluid: State-of-the-Art.
  1. Metabolomics. 2022 Dec 05. 18(12): 103
    Good practices and recommendations for using and benchmarking computational metabolomics metabolite annotation tools.
    Niek F de Jonge, Kevin Mildau, David Meijer, Joris J R Louwen, Christoph Bueschl, Florian Huber, Justin J J van der Hooft.
       BACKGROUND: Untargeted metabolomics approaches based on mass spectrometry obtain comprehensive profiles of complex biological samples. However, on average only 10% of the molecules can be annotated. This low annotation rate hampers biochemical interpretation and effective comparison of metabolomics studies. Furthermore, de novo structural characterization of mass spectral data remains a complicated and time-intensive process. Recently, the field of computational metabolomics has gained traction and novel methods have started to enable large-scale and reliable metabolite annotation. Molecular networking and machine learning-based in-silico annotation tools have been shown to greatly assist metabolite characterization in diverse fields such as clinical metabolomics and natural product discovery.
    AIM OF REVIEW: We highlight recent advances in computational metabolite annotation workflows with a special focus on their evaluation and comparison with other tools. Whilst the progress is substantial and promising, we also argue that inconsistencies in benchmarking different tools hamper users from selecting the most appropriate and promising method for their research. We summarize benchmarking strategies of the different tools and outline several recommendations for benchmarking and comparing novel tools.
    KEY SCIENTIFIC CONCEPTS OF REVIEW: This review focuses on recent advances in mass spectral library-based and machine learning-supported metabolite annotation workflows. We discuss large-scale library matching and analogue search, the current bloom of mass spectral similarity scores, and how molecular networking has changed the field. In addition, the potentials and challenges of machine learning-supported metabolite annotation workflows are highlighted. Overall, recent developments in computational metabolomics have started to fundamentally change metabolomics workflows, and we expect that as a community we will be able to overcome current method performance ambiguities and annotation bottlenecks.
    Keywords:  Benchmarking; Machine learning; Mass fragmentation spectra; Mass spectrometry; Metabolite annotation and identification; Untargeted metabolomics
    DOI:  https://doi.org/10.1007/s11306-022-01963-y
  2. J Vis Exp. 2022 11 18.
    Shotgun Lipidomics of Rodent Tissues.
    Oksana Lavrynenko, Sophie Dijon, Björn Titz, Nikolai V Ivanov.
      Lipids play a vital role as essential components of all prokaryotic and eukaryotic cells. Constant technological improvements in mass spectrometry have made lipidomics a powerful analytical tool for monitoring tissue lipidome compositions in homeostatic as well as disease states. This paper presents a step-by-step protocol for a shotgun lipid analysis method that supports the simultaneous detection and quantification of a few hundred molecular lipid species in different tissue and biofluid samples at high throughput. This method leverages automated nano-flow direct injection of a total lipid extract spiked with labeled internal standards without chromatographic separation into a high-resolution mass spectrometry instrument. Starting from sub-microgram amounts of rodent tissue, the MS analysis takes 10 min per sample and covers up to 400 lipids from 14 lipid classes in mouse lung tissue. The method presented here is well suited for studying disease mechanisms and identifying and quantifying biomarkers that indicate early toxicity or beneficial effects within rodent tissues.
    DOI:  https://doi.org/10.3791/63726
  3. Anal Chem. 2022 Dec 06.
    CCS Predictor 2.0: An Open-Source Jupyter Notebook Tool for Filtering Out False Positives in Metabolomics.
    Markace A Rainey, Chandler A Watson, Carter K Asef, Makayla R Foster, Erin S Baker, Facundo M Fernández.
      Metabolite annotation continues to be the widely accepted bottleneck in nontargeted metabolomics workflows. Annotation of metabolites typically relies on a combination of high-resolution mass spectrometry (MS) with parent and tandem measurements, isotope cluster evaluations, and Kendrick mass defect (KMD) analysis. Chromatographic retention time matching with standards is often used at the later stages of the process, which can also be followed by metabolite isolation and structure confirmation utilizing nuclear magnetic resonance (NMR) spectroscopy. The measurement of gas-phase collision cross-section (CCS) values by ion mobility (IM) spectrometry also adds an important dimension to this workflow by generating an additional molecular parameter that can be used for filtering unlikely structures. The millisecond timescale of IM spectrometry allows the rapid measurement of CCS values and allows easy pairing with existing MS workflows. Here, we report on a highly accurate machine learning algorithm (CCSP 2.0) in an open-source Jupyter Notebook format to predict CCS values based on linear support vector regression models. This tool allows customization of the training set to the needs of the user, enabling the production of models for new adducts or previously unexplored molecular classes. CCSP produces predictions with accuracy equal to or greater than existing machine learning approaches such as CCSbase, DeepCCS, and AllCCS, while being better aligned with FAIR (Findable, Accessible, Interoperable, and Reusable) data principles. Another unique aspect of CCSP 2.0 is its inclusion of a large library of 1613 molecular descriptors via the Mordred Python package, further encoding the fine aspects of isomeric molecular structures. CCS prediction accuracy was tested using CCS values in the McLean CCS Compendium with median relative errors of 1.25, 1.73, and 1.87% for the 170 [M - H]-, 155 [M + H]+, and 138 [M + Na]+ adducts tested. For superclass-matched data sets, CCS predictions via CCSP allowed filtering of 36.1% of incorrect structures while retaining a total of 100% of the correct annotations using a ΔCCS threshold of 2.8% and a mass error of 10 ppm.
    DOI:  https://doi.org/10.1021/acs.analchem.2c03491
  4. JACS Au. 2022 Nov 28. 2(11): 2548-2560
    Integrated Exposomics/Metabolomics for Rapid Exposure and Effect Analyses.
    Mira Flasch, Veronika Fitz, Evelyn Rampler, Chibundu N Ezekiel, Gunda Koellensperger, Benedikt Warth.
      The totality of environmental exposures and lifestyle factors, commonly referred to as the exposome, is poorly understood. Measuring the myriad of chemicals that humans are exposed to is immensely challenging, and identifying disrupted metabolic pathways is even more complex. Here, we present a novel technological approach for the comprehensive, rapid, and integrated analysis of the endogenous human metabolome and the chemical exposome. By combining reverse-phase and hydrophilic interaction liquid chromatography (HILIC) and fast polarity-switching, molecules with highly diverse chemical structures can be analyzed in 15 min with a single analytical run as both column's effluents are combined before analysis. Standard reference materials and authentic standards were evaluated to critically benchmark performance. Highly sensitive median limits of detection (LODs) with 0.04 μM for >140 quantitatively assessed endogenous metabolites and 0.08 ng/mL for the >100 model xenobiotics and human estrogens in solvent were obtained. In matrix, the median LOD values were higher with 0.7 ng/mL (urine) and 0.5 ng/mL (plasma) for exogenous chemicals. To prove the dual-column approach's applicability, real-life urine samples from sub-Saharan Africa (high-exposure scenario) and Europe (low-exposure scenario) were assessed in a targeted and nontargeted manner. Our liquid chromatography high-resolution mass spectrometry (LC-HRMS) approach demonstrates the feasibility of quantitatively and simultaneously assessing the endogenous metabolome and the chemical exposome for the high-throughput measurement of environmental drivers of diseases.
    DOI:  https://doi.org/10.1021/jacsau.2c00433
  5. Metabolomics. 2022 Dec 05. 18(12): 102
    Problems, principles and progress in computational annotation of NMR metabolomics data.
    Michael T Judge, Timothy M D Ebbels.
       BACKGROUND: Compound identification remains a critical bottleneck in the process of exploiting Nuclear Magnetic Resonance (NMR) metabolomics data, especially for 1H 1-dimensional (1H 1D) data. As databases of reference compound spectra have grown, workflows have evolved to rely heavily on their search functions to facilitate this process by generating lists of potential metabolites found in complex mixture data, facilitating annotation and identification. However, approaches for validating and communicating annotations are most often guided by expert knowledge, and therefore are highly variable despite repeated efforts to align practices and define community standards.
    AIM OF REVIEW: This review is aimed at broadening the application of automated annotation tools by discussing the key ideas of spectral matching and beginning to describe a set of terms to classify this information, thus advancing standards for communicating annotation confidence. Additionally, we hope that this review will facilitate the growing collaboration between chemical data scientists, software developers and the NMR metabolomics community aiding development of long-term software solutions.
    KEY SCIENTIFIC CONCEPTS OF REVIEW: We begin with a brief discussion of the typical untargeted NMR identification workflow. We differentiate between annotation (hypothesis generation, filtering), and identification (hypothesis testing, verification), and note the utility of different NMR data features for annotation. We then touch on three parts of annotation: (1) generation of queries, (2) matching queries to reference data, and (3) scoring and confidence estimation of potential matches for verification. In doing so, we highlight existing approaches to automated and semi-automated annotation from the perspective of the structural information they utilize, as well as how this information can be represented computationally.
    Keywords:  Computational annotation; Feature; Metabolite identification; NMR metabolomics; Reference database matching; Spectral comparison
    DOI:  https://doi.org/10.1007/s11306-022-01962-z
  6. Metabolomics. 2022 Dec 06. 18(12): 104
    Integrating ion mobility into comprehensive multidimensional metabolomics workflows: critical considerations.
    Jody C May, John A McLean.
       BACKGROUND: Ion mobility (IM) separation capabilities are now widely available to researchers through several commercial vendors and are now being adopted into many metabolomics workflows. The added peak capacity that ion mobility offers with minimal compromise to other analytical figures-of-merit has provided real benefits to sensitivity and structural selectivity and have allowed more specific metabolite annotations to be assigned in untargeted workflows. One of the greatest promises of contemporary IM-enabled instrumentation is the capability of operating multiple analytical dimensions inline with minimal sample volumes, which has the potential to address many grand challenges currently faced in the omics fields. However, comprehensive operation of multidimensional mass spectrometry comes with its own inherent challenges that, beyond operational complexity, may not be immediately obvious to practitioners of these techniques.
    AIM OF REVIEW: In this review, we outline the strengths and considerations for incorporating IM analysis in metabolomics workflows and provide a critical but forward-looking perspective on the contemporary challenges and prospects associated with interpreting IM data into chemical knowledge.
    KEY SCIENTIFIC CONCEPTS OF REVIEW: We outline a strategy for unifying IM-derived collision cross section (CCS) measurements obtained from different IM techniques and discuss the emerging field of high resolution ion mobility (HRIM) that is poised to address many of the contemporary challenges associated with ion mobility metabolomics. Whereas the LC step limits the throughput of comprehensive LC-IM-MS, the higher peak capacity of HRIM can allow fast LC gradients or rapid sample cleanup via solid-phase extraction (SPE) to be utilized, significantly improving the sample throughput.
    Keywords:  4-dimensional separations; Collision cross section alignment and unification; Compound identifications; Metabolite stereoisomers and charge isomers; RT-CCS-m/z triplet features
    DOI:  https://doi.org/10.1007/s11306-022-01961-0
  7. Anal Chem. 2022 Dec 06. 94(48): 16604-16613
    Novel Method for Comprehensive Annotation of Plant Glycosides Based on Untargeted LC-HRMS/MS Metabolomics.
    Xiuqiong Zhang, Fujian Zheng, Chunxia Zhao, Zaifang Li, Chao Li, Yueyi Xia, Sijia Zheng, Xinxin Wang, Xiaoshan Sun, Xinjie Zhao, Xiaohui Lin, Xin Lu, Guowang Xu.
      Glycosides are a large family of secondary metabolites in plants, which play a critical role in plant growth and development. Due to the complexity and diversity in structures and the limited availability of authentic standards, comprehensive annotation of the glycosides remains a great challenge. In this study, using maize as an example, a deep annotation method of glycosides was proposed based on untargeted liquid chromatography-high-resolution tandem mass spectrometry metabolomics analysis. First, knowledge-based in silico aglycone and glycosyl/acyl-glycosyl libraries were built. A total of 1240 known and potential aglycones from databases and literature were recorded. Next, the MS parameters beneficial to aglycone ion-rich MS/MS were explored using 1782 high-resolution MS/MS spectra of glycosides from the MassBank of North America (MoNA) and confirmed by 52 authentic glycoside standards. Then, screening rules for aglycon ions in MS/MS were recommended. Glycoside candidates were further filtered by MS/MS-based chemical classification and MS/MS similarity of aglycon-glycoside pairs. Finally, the glycosylation sites of flavonoid mono-O-glycosides were recommended by characteristic fragmentation patterns. The developed method was validated using glycosides and nonglycosides from the MoNA library. The annotation accuracy rates were 96.8, 94.9, and 98.0% in negative ion mode (ESI-), positive ion mode (ESI+), and the combined ESI- & ESI+, respectively. The annotation specificity was 99.6% (ESI-), 99.6% (ESI+), and 99.2% (ESI- & ESI+). A total of 274 glycosides (including 34 acyl-glycosides) were tentatively annotated in maize by the developed method. The method enables effective and reliable annotation for plant glycosides.
    DOI:  https://doi.org/10.1021/acs.analchem.2c02362
  8. J Chromatogr B Analyt Technol Biomed Life Sci. 2022 Nov 28. pii: S1570-0232(22)00457-3. [Epub ahead of print]1214 123552
    Development and validation of an analytical method using liquid chromatography-tandem mass spectrometry for the therapeutic drug monitoring of seven cardiovascular drugs in clinical usage.
    Mariam M Abady, Ji-Seon Jeong, Ha-Jeong Kwon.
      Therapeutic drug monitoring (TDM) of cardiovascular drugs is essential to improve treatment efficacy and minimize toxicity because of the usage of multiple drugs with a very limited therapeutic range and the high pharmacokinetic variation in patients. We developed and validated a reliable and economical liquid chromatography/tandem mass spectrometry (LC-MS/MS) method for the determination of seven cardiovascular drugs-procainamide, lidocaine, quinidine, deslanoside, digoxin, atorvastatin, and digitoxin-for clinical usage. Serum samples were prepared by simple protein precipitation with an organic solvent consisting of acetonitrile and methanol (2:1 v/v) and analyzed under optimized LC-MS/MS conditions. The chromatographic separations were accomplished within 15 min on a reversed-phase C18 column with a gradient elution of aqueous solvent and acetonitrile while maintaining 0.1 (v/v) % formic acid and 2 mM ammonium formate. The optimized MS/MS conditions in ESI-positive mode offered sufficient sensitivity for the seven cardiovascular drugs (LOQs between 0.5 and 1 ng/mL). This method was fully validated including linearity, selectivity, accuracy, precision, carry-over, and matrix effects. Additionally, stability under several conditions was tested to determine how to handle the standard solutions and serum samples. The seven cardiovascular drugs, simultaneously, were precisely and accurately analyzed in intra- and inter-day assays (RSD < 6 % and recovery between 96.3 and 102.8 %) using only two isotope-labeled internal standards (lidocaine-(diethyl-d10) and digoxin-21, 21, 22-d3). The presented method also showed good accuracy in analyzing the seven drugs in hyperlipidemia, hyperalbuminemia, and hyperglycemia serum, allowing it to be recommended as a common and routine analysis method for cardiovascular drugs in clinical practice.
    Keywords:  Cardiovascular drug; Human serum; LC-MS/MS; Method validation; Sample preparation; Therapeutic drug monitoring
    DOI:  https://doi.org/10.1016/j.jchromb.2022.123552
  9. J Mass Spectrom. 2022 Dec;57(12): e4897
    Method validation and clinical application for the quantification of lopinavir, efavirenz, and ritonavir in breast milk using liquid chromatography tandem mass spectrometry.
    Francois Fraissinet, Aboubacar A Oumar, Patrick Seraissol, Marie Christine Cere, Michel Lavit, Etienne Chatelut, Peggy Gandia.
      A liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been validated for quantification of three antiretroviral drugs (efavirenz [EFV], lopinavir [LPV], and ritonavir [RTV]) from human breast milk. The samples were extracted employing protein precipitation method using methanol as precipitating agent. The supernatant was evaporated and reconstituted before injecting into the chromatograph and separated on a biphenyl column. Calibration curves for the three tested antiretroviral drugs were linear (r ≥ 0.999) over the range examined. The inter- and intra-day coefficients of variation (CV) were ≤15% for efavirenz, lopinavir, and ritonavir. Mean recovery ranged from 96% to 105% and no major matrix effects were observed. This validated LC-MS/MS method was efficiently applied to determine EFV, LPV, and RTV concentrations in breast milk from Human Immunodeficiency Virus (HIV)-positive breastfeeding mothers. This assay requires a simple sample processing method with a short run time, making it well suited for high-throughput routine clinical or research purposes.
    Keywords:  breast milk; efavirenz; lopinavir; mass spectrometry; ritonavir
    DOI:  https://doi.org/10.1002/jms.4897
  10. JACS Au. 2022 Nov 28. 2(11): 2466-2480
    Decoding Distinct Ganglioside Patterns of Native and Differentiated Mesenchymal Stem Cells by a Novel Glycolipidomics Profiling Strategy.
    Katharina Hohenwallner, Nina Troppmair, Lisa Panzenboeck, Cornelia Kasper, Yasin El Abiead, Gunda Koellensperger, Leonida M Lamp, Jürgen Hartler, Dominik Egger, Evelyn Rampler.
      Gangliosides are an indispensable glycolipid class concentrated on cell surfaces with a critical role in stem cell differentiation. Nonetheless, owing to the lack of suitable methods for scalable analysis covering the full scope of ganglioside molecular diversity, their mechanistic properties in signaling and differentiation remain undiscovered to a large extent. This work introduces a sensitive and comprehensive ganglioside assay based on liquid chromatography, high-resolution mass spectrometry, and multistage fragmentation. Complemented by an open-source data evaluation workflow, we provide automated in-depth lipid species-level and molecular species-level annotation based on decision rule sets for all major ganglioside classes. Compared to conventional state-of-the-art methods, the presented ganglioside assay offers (1) increased sensitivity, (2) superior structural elucidation, and (3) the possibility to detect novel ganglioside species. A major reason for the highly improved sensitivity is the optimized spectral readout based on the unique capability of two parallelizable mass analyzers for multistage fragmentation. We demonstrated the high-throughput universal capability of our novel analytical strategy by identifying 254 ganglioside species. As a proof of concept, 137 unique gangliosides were annotated in native and differentiated human mesenchymal stem cells including 78 potential cell-state-specific markers and 38 previously unreported gangliosides. A general increase of the ganglioside numbers upon differentiation was observed as well as cell-state-specific clustering based on the ganglioside species patterns. The combination of the developed glycolipidomics assay with the extended automated annotation tool enables comprehensive in-depth ganglioside characterization as shown on biological samples of interest. Our results suggest ganglioside patterns as a promising quality control tool for stem cells and their differentiation products. Additionally, we believe that our analytical workflow paves the way for probing glycolipid-based biochemical processes shedding light on the enigmatic processes of gangliosides and glycolipids in general.
    DOI:  https://doi.org/10.1021/jacsau.2c00230
  11. J Mass Spectrom. 2022 Dec;57(12): e4898
    On the importance of color in mass spectrometry imaging.
    Kevan T Knizner, Russell R Kibbe, Kenneth P Garrard, Jamie R Nuñez, Christopher R Anderton, David C Muddiman.
      Mass spectrometry imaging (MSI) data visualization relies on heatmaps to show the spatial distribution and measured abundances of molecules within a sample. Nonuniform color gradients such as jet are still commonly used to visualize MSI data, increasing the probability of data misinterpretation and false conclusions. Also, the use of nonuniform color gradients and the combination of hues used in common colormaps make it challenging for people with color vision deficiencies (CVDs) to visualize and accurately interpret data. Here we present best practices for choosing a colormap to accurately display MSI data, improve readability, and accommodate all CVDs. We also provide other resources on the misuse of color in the scientific field and resources on scientifically derived colormaps presented herein.
    Keywords:  CVD; MSI; colormap; data visualization
    DOI:  https://doi.org/10.1002/jms.4898
  12. Anal Chem. 2022 Dec 06.
    Mass Spectrometry Imaging of Lipids Using MALDI Coupled with Plasma-Based Post-Ionization on a Trapped Ion Mobility Mass Spectrometer.
    Jesse A Michael, Shadrack M Mutuku, Boris Ucur, Tassiani Sarretto, Alan T Maccarone, Marcel Niehaus, Adam J Trevitt, Shane R Ellis.
      Here we report the development and optimization of a mass spectrometry imaging (MSI) platform that combines an atmospheric-pressure matrix-assisted laser desorption/ionization platform with plasma postionization (AP-MALDI-PPI) and trapped ion mobility spectrometry (TIMS). We discuss optimal parameters for operating the source, characterize the behavior of a variety of lipid classes in positive- and negative-ion modes, and explore the capabilities for lipid imaging using murine brain tissue. The instrument generates high signal-to-noise for numerous lipid species, with mass spectra sharing many similarities to those obtained using laser postionization (MALDI-2). The system is especially well suited for detecting lipids such as phosphatidylethanolamine (PE), as well as numerous sphingolipid classes and glycerolipids. For the first time, the coupling of plasma-based postionization with ion mobility is presented, and we show the value of ion mobility for the resolution and identification of species within rich spectra that contain numerous isobaric/isomeric signals that are not resolved in the m/z dimension alone, including isomeric PE and demethylated phosphatidylcholine lipids produced by in-source fragmentation. The reported instrument provides a powerful and user-friendly approach for MSI of lipids.
    DOI:  https://doi.org/10.1021/acs.analchem.2c03745
  13. Anal Chim Acta. 2023 Jan 15. pii: S0003-2670(22)00760-7. [Epub ahead of print]1238 340189
    Image classification combined with faster R-CNN for the peak detection of complex components and their metabolites in untargeted LC-HRMS data.
    Jun Zeng, Hai Wu, Min He.
      Peak detection of untargeted liquid chromatography-high resolution mass spectrometry (LC-HRMS) data is a key step to identify the metabolic status of the drugable chemicals and extracts from functional foods or herbs. Nevertheless, the existing approaches are difficult to obtain ideal results with low false positives and false negatives. In this paper, we proposed an automatic method based on convolutional neural network (CNN) for image classification and Faster R-CNN for peak location/classification in untargeted LC-HRMS data, and named it Peak_CF. It can achieve detection of target peaks with high accuracy and high recall (both >90%) as verified by an evaluation data-set. In terms of detecting the m/z peaks of known compounds, Peak_CF is better than Peakonly, and it can effectively have an overall peak shape judgment of split peaks. For the same evaluation data, the recall of MZmine2 (ADAP) is slightly higher than that of Peak_CF, however, the F1 score of Peak_CF is higher, indicating that it has higher accuracy. In addition, the Peak_ CF training model with strong generalization ability can be achieved and verified. At last, Peak_CF was applied in real metabolic fingerprints of total flavonoids from Glycyrrhiza uralensis Fisch, also a contrast was conducted based on 40 m/z peaks of 40 prototypes in serum data-set. The result showed that the recall rate of Peak_CF and Peakonly all reached 95%, higher than 70% of MZmine2 (ADAP), and Peak_CF is more accurate when detecting EIC that has serious drifts. In conclusion, Peak_CF provides a new route for data mining of LC-HRMS datasets of drug (or herbs, or functional foods) metabolites.
    Keywords:  CNN; Faster R–CNN; LC-HRMS; Metabolic fingerprints; Peak detection
    DOI:  https://doi.org/10.1016/j.aca.2022.340189
  14. J Chromatogr A. 2022 Nov 14. pii: S0021-9673(22)00842-1. [Epub ahead of print]1687 463651
    Trace determination of prohibited acrylamide in cosmetic products by vortex-assisted reversed-phase dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry.
    Lorenza Schettino, Alejandro García-Juan, Laura Fernández-Lozano, Juan L Benedé, Alberto Chisvert.
      An analytical method for the determination of residual acrylamide in cosmetic products containing potential acrylamide-releasing ingredients is presented. The method is based on vortex-assisted reversed-phase dispersive liquid-liquid microextraction (VA-RP-DLLME) to extract and preconcentrate acrylamide by using water as extraction solvent taking advantage the highly polar behavior of this analyte, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for its determination. Under optimized conditions (5 mL toluene as supporting solvent, 50 µL of water as extraction solvent, 1 min for vortex extraction time) the method was properly validated obtaining good analytical features (linearity up to 20 ng mL-1, method limits of detection and quantification of 0.51 and 1.69 ng g-1, respectively, enrichment factor of 52, and good repeatability (RSD < 4.1%)). The proposed analytical method was applied to the determination of acrylamide in commercial samples that were weighed and dispersed in the minimum quantity of methanol (50 µL) by vortex stirring before applying the VA-RP-DLLME procedure. Through the pretreatment of the sample and the use of acrylamide-d3 as surrogate, the matrix effect was overcome, obtaining good relative recovery values (88-108%). The proposed method has shown efficacy, simplicity, and speed, and it allows the determination of acrylamide at trace levels easily, which could make it very useful for companies in the quality control of cosmetic products containing potential acrylamide-releasing ingredients to fulfill the safety limits imposed by European Regulation.
    Keywords:  Acrylamide; Cosmetic products; Liquid chromatography-mass spectrometry; Reversed-phase dispersive liquid-liquid microextraction
    DOI:  https://doi.org/10.1016/j.chroma.2022.463651
  15. J Proteome Res. 2022 Dec 09.
    Comprehensive Profiling of Phosphomonoester Metabolites in Saccharomyces cerevisiae by the Chemical Isotope Labeling-LC-MS Method.
    Sha Li, Zheng Zhang, Fei-Long Liu, Bi-Feng Yuan, Tian-Gang Liu, Yu-Qi Feng.
      Phosphomonoesters are important biosynthetic and energy metabolism intermediates in microorganisms. A comprehensive analysis of phosphomonoester metabolites is of great significance for the understanding of their metabolic phosphorylation process and inner mechanism. In this study, we established a pair of isotope reagent d0/d5-2-diazomethyl-N-methyl-phenyl benzamide-labeling-based LC-MS method for the comprehensive analysis of phosphomonoester metabolites. By this method, the labeled phosphomonoester metabolites specifically produced characteristic isotope paired peaks with an m/z difference of 5.0314 in the MS1 spectra and a pair of diagnostic ions (m/z 320.0693/325.1077) in the MS2 spectra. Based on this, a diagnostic ion-based strategy was established for the rapid screening, identification, and relative quantification of phosphomonoester metabolites. Using this strategy, 42 phosphomonoester metabolites were highly accurately identified fromSaccharomyces cerevisiae (S. cerevisiae). Notably, two phosphomonoesters were first detected fromS. cerevisiae. The relative quantification results indicated that the contents of nine phosphomonoester metabolites including two intermediates (Ru5P and S7P) in the pentose phosphate pathway (PPP) were significantly different between lycopene-producible and wild-type S. cerevisiae. A further enzyme assay indicated that the activity of the PPP was closely related to the production of lycopene. Our findings provide new perspectives for the related mechanism study and valuable references for making informed microbial engineering decisions.
    Keywords:  LC−MS; chemical isotope labeling; lycopene-producible S. cerevisiae; phosphomonoester metabolites
    DOI:  https://doi.org/10.1021/acs.jproteome.2c00507
  16. J Pharm Biomed Anal. 2022 Nov 24. pii: S0731-7085(22)00589-1. [Epub ahead of print]224 115168
    Chiral LC-MS/MS method for the simultaneous determination of (R,S)-ketamine, (R,S)-norketamine, and (2R,6R;2S,6S)-hydroxynorketamine in mouse plasma and brain.
    Hidetoh Toki, Jun-Ichi Yamaguchi, Akiko Mizuno-Yasuhira, Hiromi Endo.
      A convenient LC-MS/MS assay method to simultaneously and sensitively determine (R,S)-ketamine (Ket), (R,S)-norketamine (NK), and (2R,6R;2S,6S)-hydroxynorketamine (HNK) enantiomers in plasma and brain from mice was developed. This method enables the chiral separations of these six enantiomers in one analysis by constructing a column-switching system composed of one achiral column and two chiral columns with a relatively short analysis time (17 min). The chromatography involves the separation of (2R,6R;2S,6S)-HNK from (R,S)-Ket and (R,S)-NK on an octadecyl-silica column, followed by chiral separations on a CHIRALPAK AY-RH column for (2R,6R;2S,6S)-HNK or on a CHIRALPAK AS-RH column for the other analytes. The calibration curves for plasma and brain showed a good linearity in the range of 3-1000 ng/mL and 1.5-500 ng/g, respectively. The accuracy ranged from 90.0% to 104.0% in within-run and between-run. This validated method was applicable to determine the stereoselective pharmacokinetic profiles of (R,S)-Ket, (R,S)-NK, and (2R,6R;2S,6S)-HNK in plasma and brain collected from individual mice after a single intraperitoneal dosing of racemic Ket at an antidepressant dose. It is hoped that this assay will greatly help for understanding the relationship between the antidepressant actions of (R,S)-Ket enantiomers or their metabolites and their pharmacokinetics.
    Keywords:  (2R,6R; (R,S)-ketamine; (R,S)-norketamine; 2S,6S)-hydroxynorketamine; Chiral LC-MS/MS; Mice; Pharmacokinetics
    DOI:  https://doi.org/10.1016/j.jpba.2022.115168
  17. J Chromatogr Sci. 2022 Dec 06. pii: bmac098. [Epub ahead of print]
    Analysis of 12 Chemical Compounds And Pattern Recognition of Different Parts of Angelicae Sinensis Radix by Liquid Chromatography-Tandem Mass Spectrometry And Chemometrics Methods.
    Shuang-Li Zhao, Fei Fu, Bo-Yang Yu, Ren-Shi Li.
      To evaluate the quality and quantify bioactive constituents in different parts of Angelicae Sinensis Radix, an efficient, high-speed, high-sensitivity high-performance liquid chromatography and triple quadrupole mass spectrometry method was used for simultaneous detection of 12 chemical compounds including L-tryptophan, chlorogenic acid, caffeic acid, ferulic acid, isoferulic acid, senkyunolide I, guanosine, proline, L-glutamine, γ-aminobutyric acid, glutamic acid, and arginine in 52 batches of Angelicae Sinensis Radix from Gansu, China. The established methods were validated by good linearity (R2≥0.9921), limits of detection (0.0001-0.0156 μg/mL), limits of quantitation (0.0006-0.0781 μg/mL), stability (RSD≤7.77%), repeatability (RSD≤6.79%), intra- and interday precisions (RSD≤6.00% and RSD≤6.39%, respectively) and recovery (90.90-107.16%). According to the quantitative results, the contents of the hydrophilic compounds were higher in the head, while the medium and weak polar components were mainly concentrated in the tail. Finally, principal component analysis results revealed that Angelicae Sinensis Radix could be divided into different medicinal sites based on polar components such as amino acids, nucleosides. The combination of liquid chromatography-tandem mass spectrometry and principal component analysis is a simple and reliable method for pattern recognition and quality evaluation of Angelicae Sinensis Radix.
    DOI:  https://doi.org/10.1093/chromsci/bmac098
  18. Anal Bioanal Chem. 2022 Dec 09.
    Rapid, sensitive, and high-throughput quantification of broad serological ceramides by using isotope dilution liquid chromatography-negative ion electrospray tandem mass spectrometry.
    Shuailong Chen, Xuan Li, Shijia Liu, Longshan Zhao, Wenyong Zhang, Zhili Xiong, Hemi Luan.
      Ceramides are important intermediates in the metabolism of sphingolipids. High-throughput liquid chromatography-mass spectrometry has been used extensively for monitoring the levels of serological ceramides, but is still limited by inadequate coverage or lack of sensitivity. Herein, a rapid, sensitive, and high-throughput isotope dilution liquid chromatography-negative ion electrospray tandem mass spectrometry (IDLC-nESI-MS/MS) method was developed and verified for accurate quantification of 41 ceramides, involving ceramides with C16-20 sphingosine, dihydro-ceramide, and dehydro-ceramide. This method was validated with excellent linearity (R2 > 0.99) and good recovery in the range of 90-110%. Intra- and inter-day imprecision were below 5.57% and 7.83% respectively. The improved high-throughput quantitative method developed in this study may aid in the accurate characterization of ceramides for understanding ceramide biology and application in disease diagnosis.
    Keywords:  Ceramide; High-throughput; Liquid chromatography; Tandem mass spectrometry
    DOI:  https://doi.org/10.1007/s00216-022-04473-x
  19. Crit Rev Anal Chem. 2022 Dec 04. 1-19
    A Review on Spike and Recovery Method in Analytical Method Development and Validation.
    Diksha Thakur, Neeti Prakash Dubey, Rajvinder Singh.
      In multidisciplinary science, Analytical approaches based on spike and recovery (SAR) play a substantial role in analytical testing. The spike and recovery method is an important technique for analyzing and accessing the accuracy of analytical methods. The goal of this review seeks to provide clarity on the role of SAR methods in the forensic science discipline. Recent literature has been searched from numerous databases like Google, Web of Sciences, Scopus, PubMed, Google Scholar, and SciFinder. Websites like Science Direct are critically explored to gather scientific reports related to SAR utility. This review discusses the applications and current role of the SAR methods in Forensic Toxicology. It is suggested as one of the major parameters in the validation of the analytical method. SAR methodology is extremely important for the identification and quantitation of analytes in the sample matrix. Moreover, the extension of SAR methods to any scientific discipline is equally important for quality assurance. All relevant processes like method development and its optimization, quality control, and assurance rely on SAR-based studies. However, the method requires better apprehension and needs to be utilized using standard guidelines.
    Keywords:  Forensic Toxicology; Method Validation; Quality Assurance; Recovery; Spike
    DOI:  https://doi.org/10.1080/10408347.2022.2152275
  20. Methods Mol Biol. 2023 ;2560 257-265
    Metabolite Extraction from RPE Cells and Retinas Related to Retinitis Pigmentosa.
    Xuan Cui, Ya-Ju Chang, Laura A Jenny, Sarah R Levi, Jianhai Du, Stephen H Tsang.
      The application of metabolomics in ophthalmology helps to identify new biomarkers and elucidate disease mechanisms in different eye diseases, as well as aiding in the development of potential treatment options. Extracting metabolites successfully is essential for potential further analysis using mass spectrometry. In this chapter, we describe how to extract metabolites from a variety of sources including (1) cells on a dish, (2) cell culture medium, and (3) tissues in vivo with and without stable isotope tracers. Samples prepared using this protocol are suitable for a range of downstream mass spectrometry analyses and are stable in solvent for weeks at -80 °C.
    Keywords:  Gas or liquid chromatography with mass spectrometric detection (GC-MS and LC-MS); Metabolites extraction; Metabolomics; RPE cells; Retina dissection
    DOI:  https://doi.org/10.1007/978-1-0716-2651-1_24
  21. J Chromatogr Sci. 2022 Dec 03. pii: bmac094. [Epub ahead of print]
    A Validated UHPLC-MS/MS Method for Determination of Nalbuphine in Human Plasma and Application for Pharmacokinetic Study of Patients Undergoing General Anesthesia.
    Xiaonan Gao, Xuyang Nie, Jinglin Gao, Tianfang Heng, Yuqi Zhang, Li Hua, Yaqi Sun, Zhangying Feng, Li Jia, Mingxia Wang.
      Nalbuphine was a semisynthetic opioid analgesic widely used in the treatment of both acute and chronic pain. We developed and validated a rapid, simple and sensitive method by ultra-performance liquid chromatography-tandem mass spectrometry (MS/MS) for the simultaneous quantitation of nalbuphine in human plasma, and we reported the pharmacokinetic features of patients during general anesthesia for abdominal surgery. Sample separation was achieved on a Kinetex Phenyl-Hexyl column (50 × 2.1 mm, 1.7 μm) after simple protein precipitation with acetonitrile. The mobile phase was composed of acetonitrile and 3 mM of ammonium acetate aqueous solution with 0.1% formic acid. Gradient elution was used in 4.5 min with a flow rate of 0.5 mL/min at 40°C. MS detection using AB Sciex QTRAP 5500 mass spectrometer was characterized by electrospray ionization for positive ions in multiple reaction monitoring mode. Quantitative ion pairs were m/z 358.4 → 340.1 for nalbuphine and m/z 340.0 → 268.3 for nalmefene, which were used as the internal standard (IS). The calibration curves showed good linearity (r2>0.99) over concentration range of 0.1-500 ng/mL. The intra-and inter-batch precisions were within 10.67%, and accuracy ranged from 94.07 to 105.34%. The IS-normalized matrix factors were 1.02-1.03 with RSD% (≤5.82%). The recoveries ranged from 101.09 to 106.30%. In conclusion, a rapid, simple, sensitive and economical analytical method was developed and validated to detect the concentration in plasma samples obtained from patients receiving nalbuphine intravenous injection and was successfully applicated to human pharmacokinetic studies of nalbuphine.
    DOI:  https://doi.org/10.1093/chromsci/bmac094
  22. J Chromatogr Sci. 2022 Dec 06. pii: bmac097. [Epub ahead of print]
    Quantification of Remimazolam Besylate (CNS7056B) and Its Metabolite (CNS7054X) by LC-MS/MS in Human Plasma Using Midazolam-d4 Maleate as Internal Standard.
    Stefanie Schmidt, Ljubica Krajinovic, Christian Mertens, Lisa Schramm, Jürgen Schüttler, Jörg Fechner.
      A new assay was developed to measure the concentration of remimazolam besylate (CNS7056B) and its major carboxylic acid metabolite (CNS7054X) in human plasma. For this new assay method, midazolam-d4 maleate was used as an internal standard. After setting up a previously described assay method, using CNS7056-d4 and CNS7054-d4 as internal standards, analytical results of both methods were compared. For the new analytical method, ultra-high-performance liquid chromatography (UHPLC) with tandem mass spectrometry was applied. A purification method, using solid phase extraction, was developed and validated. The chromatographic separation of the analytes was achieved with a mobile phase gradient using a Water Acquity™ UHPLC-System. The Kinetex™ biphenyl 50 × 2.1 mm UHPLC column was used with a particle diameter of 1.7 μm (Phenomenex, Germany). A measuring range of 0.6-2,000 ng/mL for CNS7056B and of 6-20,000 ng/mL for CNS7054X could be achieved with this new assay. The lower limit of quantification was 0.6 ng/mL for CNS7056B and 6 ng/mL for CNS7054X. The assay was validated according to US Food and Drug Administration guidelines. The new method showed an accuracy of 96.9-110.4% and a precision of 2.1-6.7% for both analytes.
    DOI:  https://doi.org/10.1093/chromsci/bmac097
  23. Anal Chim Acta. 2023 Jan 15. pii: S0003-2670(22)01198-9. [Epub ahead of print]1238 340627
    New challenges in sample preparation: Miniaturized stir bar sorptive dispersive microextraction as a high-throughput and feasible approach for low-availability sample preparation.
    Cristian Azorín, Juan L Benedé, Alberto Chisvert.
      The miniaturization of stir bar sorptive dispersive microextraction (mSBSDME) for the analysis of low-availability samples is presented. This new methodology is based on the principles of stir bar sorptive dispersive microextraction, but the amount of sorbent and, most importantly, the amount of sample are considerably reduced to a tiny amount and a few microliters, respectively. Thus, affordable 400-μL flat-base glass inserts and minute bar-shape neodymium magnets (3 mm length x 2 mm diameter) were used as extraction devices hold by a specifically designed multiextraction assembly, which comprises a high-rate stirring plate and a 3D-printed support to treat 15 samples simultaneously. This new approach allows a fast, affordable, portable, and high-throughput analysis of low-volume samples, expanding the potential of the technique. The same extraction device is used along the different stages, thus avoiding transfers, which reduces sample handling. Besides, the reduction in the sample, sorbent and organic solvent amounts allows a considerable decrease of the waste generation, and thus pursues a green sample preparation for bioanalysis. As a proof-of-concept of this new methodology, cortisone and cortisol were determined in human saliva using a composite material made of a reversed phase polymer (Strata™-X-RP) and CoFe2O4 magnetic nanoparticles. Liquid chromatography coupled to tandem mass spectrometry was used to measure both analytes obtaining good analytical features in terms of linearity (R2 > 0.997), method limits of detection and quantification (22.6 and 75.5 ng L-1 for cortisone, and 19.3 and 64.3 ng L-1 for cortisol, respectively), repeatability (RSD ≤11%) and relative recoveries (78-134%).
    Keywords:  Biomarkers; Cortisol; Cortisone; Dispersive-based microextraction; Human saliva; Magnetic sorbent; Miniaturization; Stir bar sorptive dispersive microextraction
    DOI:  https://doi.org/10.1016/j.aca.2022.340627
  24. Talanta. 2022 Nov 19. pii: S0039-9140(22)00911-0. [Epub ahead of print]254 124115
    Rapid determination of polyethoxylated tallow amine surfactants in human plasma by LC-MSMS.
    Shuping Qiang, Fahim Mohamed, Lorraine Mackenzie, Michael S Roberts.
      The potential exposure to the widely used glyphosate-based herbicides, including attempted suicide by ingestion, is of world-wide concern. Whilst the major focus to date has been on managing exposure to the active ingredient glyphosate, it is now recognised that a common major 'inert' surfactant ingredient, polyethoxylated tallow amine (POEA) and related compounds, may be more toxic. However, the information on the toxicokinetics of POEA surfactants after exposure is limited, in part, due to the lack of suitable methods for their analysis in biological matrices. We therefore developed and validated a robust LC-MSMS method that allowed, for the first time, a rapid analysis of 11 POEA homologues in human plasma. Chromatographic separation was achieved on a Kinetex EVO C18 column under a 5 min gradient elution with mobile phase A containing water/acetonitrile/formic acid (95:5:0.1, v/v/v) and mobile phase B containing acetonitrile/water/formic acid (95:5:0.1, v/v/v). Amlodipine was chosen as the internal standard (IS) for this assay. Amlodipine-d4 would be an ideal alternative IS to expand the applicability of the established method especially in antihypertensive patients. Multiple reaction monitoring (MRM) methods were optimized for 11 POEA homologues and the IS. Sample pre-treatment was performed using simple protein precipitation with methanol at a ratio of 4:1, requiring only 20 μL plasma. The validated method showed good specificity, accuracy and precision with lower limits of quantification (LLOQ) ranging from 0.35 to 10.8 ng mL-1 for all selected POEA homologues. The method was then used to measure concentrations of the various POEA surfactants in more than 600 human plasma samples from 151 patients admitted to hospital with acute glyphosate intoxication. The highest concentrations ranged from 1.07 ng mL-1 for C18u(EO)4-362.70 ng mL-1 for C16s(EO)2. The analysis of POEA surfactants plasma concentrations as described here underpins the assessment of POEA internal exposure and the relationships between POEA related glyphosate toxicity and the extent of poisoning.
    Keywords:  Glyphosate; Herbicide poisoning; Liquid chromatography-tandem mass spectrometry (LC-MSMS); Plasma; Polyethoxylated tallow amine; Surfactant
    DOI:  https://doi.org/10.1016/j.talanta.2022.124115
  25. Anal Methods. 2022 Dec 09.
    Different approaches for estimation of the expanded uncertainty of an analytical method developed for determining pharmaceutical active compounds in wastewater using solid-phase extraction and a liquid chromatography coupled with tandem mass spectrometry method.
    João A Rodrigues, Sofia Silva, Vitor Vale Cardoso, Maria João Benoliel, Cristina M M Almeida.
      Although the evaluation of the uncertainty of an analytical method is a mandatory step in the method's validation, its applicability to the monitoring of trace compounds in complex samples is not simple, nor is it part of the routine of most laboratories, namely those dedicated to research. This manuscript focuses on the full validation of an analytical procedure for determining trace concentrations of twenty-four pharmaceutical active compounds (PhACs) in wastewaters using solid-phase extraction (SPE) and ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The method optimization was performed on different wastewater matrices, namely influents and final effluents from two distinct wastewater treatment plants (WWTPs). Matrix effects and extraction efficiency (absolute recovery) of the developed method were determined. Validation was performed to obtain the method's linearity/working range, precision, trueness, method detection limits (MDLs) and method quantification limits (MQLs). The expanded uncertainty of the data obtained was estimated according to the requirements of international procedures dedicated to the expression of uncertainty. Different approaches for the estimation of uncertainty were applied. The validated method was used in the analysis of target PhACs in wastewater samples collected at two WWTPs. The obtained results facilitated the introduction of a validated method for routine measurement of PhACs in wastewater samples and allowed method accreditation by the competent national authority.
    DOI:  https://doi.org/10.1039/d2ay01676a
  26. Bioanalysis. 2022 Dec 06.
    Validation of an LC-MS/MS method for the determination of sotorasib, a KRASG12C inhibitor, in human plasma.
    Philip Wong, Anna Akrami, Brett Houk, Irene Vuu, Christopher A James.
      Background: Sotorasib (AMG 510) is a first-in-class KRASG12C inhibitor that received accelerated US FDA approval in 2021 for the treatment of patients with KRASG12C-mutated locally advanced or metastatic non-small-cell lung cancer. Method: An LC-MS/MS method was developed and validated for the determination of sotorasib in human plasma to support clinical development studies. Samples were prepared using protein precipitation and analyzed by LC-MS/MS using gradient elution with a calibration standard curve range of 10.0-10,000 ng/ml. Stable isotope labeled [13C, D3]-sotorasib was used as an internal standard. Results and conclusion: The method fully met FDA guidelines for all validation parameters, including precision, accuracy, selectivity, matrix effect, recovery and stability and has been extensively used to support multiple clinical studies.
    Keywords:  KRAS inhibitor; KRASG12C; LC–MS; chromatography; clinical; mass spectrometry; oncology; sotorasib; validation
    DOI:  https://doi.org/10.4155/bio-2022-0173
  27. Anal Chem. 2022 Dec 06.
    Analysis of the Amine Submetabolome Using Novel Isotope-Coded Pyrylium Salt Derivatization and LC-MS: Herbs and Cancer Tissues as Cases.
    Li Liu, Geng-Yu Bao, Shu-Sheng Zhang, Yong Qin, Xiu-Ping Chen, Ming-Dan Wang, Jian-Ping Zhu, Hang Yin, Guo-Qiang Lin, Chen-Guo Feng, Fang Zhang, Yin-Long Guo.
      The amine submetabolome, including amino acids (AAs) and biogenic amines (BAs), is a class of small molecular compounds exhibiting important physiological activities. Here, a new pyrylium salt named 6,7-dimethoxy-3-methyl isochromenylium tetrafluoroborate ([d0]-DMMIC) with stable isotope-labeled reagents ([d3]-/[d6]-DMMIC) was designed and synthesized for amino compounds. [d0]-/[d3]-/[d6]-DMMIC-derivatized had a charged tag and formed a set of molecular ions with an increase of 3.02 m/z and the characteristic fragment ions of m/z 204.1:207.1:210.1. When DMMIC coupled with liquid chromatography-mass spectrometry (LC-MS), a systematic methodology evaluation for quantitation proved to have good linearity (R2 between 0.9904 and 0.9998), precision (interday: 2.2-21.9%; intraday: 1.0-19.7%), and accuracy (recovery: 71.8-108.8%) through the test AAs. Finally, the methods based on DMMIC and LC-MS demonstrated the advantaged application by the nontargeted screening of BAs in a common medicinal herb Senecio scandens and an analysis of metabolic differences among the amine submetabolomes between the carcinoma and paracarcinoma tissues of esophageal squamous cell carcinoma (ESCC). A total of 20 BA candidates were discovered in S. scandens as well as the finding of 13 amine metabolites might be the highest-potential differential metabolites in ESCC. The results showed the ability of DMMIC coupled with LC-MS to analyze the amine submetabolome in herbs and clinical tissues.
    DOI:  https://doi.org/10.1021/acs.analchem.2c04246
  28. Bioanalysis. 2022 Dec 06.
    Development and validation of an LC-MS/MS method to quantify kynurenic acid in human plasma.
    Renmeng Liu, Xiaofeng Zhao, Guoju Geng, Yurong Lai.
      Background: Monitoring levels of endogenous biomarkers has become an alternative approach to assess transporter-mediated drug-drug interactions in clinical trials. Among the biomarkers of interest, kynurenic acid is effective for the human organic anion transporters OAT1 and OAT3. Here, a simple and robust bioanalytical method was developed using LC-MS/MS to quantify kynurenic acid in human plasma. Results: This method achieved a LLOQ of 10 nm with acceptable signal-to-noise ratio (S/N >5). In addition, an interfering agent, tryptophan, was identified and separated chromatographically. A full method validation was performed in the spirit of GLP. Conclusion: This method can serve as a tool readily available to assess potential drug-drug interactions mediated by inhibition of OAT1 and OAT3 activities.
    Keywords:  LC–MS/MS; biomarker; drug–drug interactions; kynurenic acid; renal transporters
    DOI:  https://doi.org/10.4155/bio-2022-0177
  29. J Chromatogr A. 2022 Nov 22. pii: S0021-9673(22)00847-0. [Epub ahead of print]1687 463656
    A rapid and systematic approach for the optimization of radio thin-layer chromatography resolution.
    Travis S Laferriere-Holloway, Alejandra Rios, Yingqing Lu, Chelsea C Okoro, R Michael van Dam.
      Radiopharmaceutical analysis is limited by conventional methods. Radio-HPLC may be inaccurate for some compounds (e.g., 18F-radiopharmaceuticals) due to radionuclide sequester. Radio-TLC is simpler, faster, and detects all species but has limited resolution. Imaging-based readout of TLC plates (e.g., using Cerenkov luminescence imaging) can improve readout resolution, but the underlying chromatographic separation efficiency may be insufficient to resolve chemically similar species such as product and precursor-derived impurities. This study applies a systematic mobile phase optimization method, PRISMA, to improve radio-TLC resolution. The PRISMA method optimizes the mobile phase by selecting the correct solvent, optimizing solvent polarity, and optimizing composition. Without prior knowledge of impurities and by simply observing the separation resolution between a radiopharmaceutical and its nearest radioactive or non-radioactive impurities (observed via UV imaging) for different mobile phases, the PRISMA method enabled the development of high-resolution separation conditions for a wide range of 18F-radiopharmaceuticals ( [18F]PBR-06, [18F]FEPPA, [18F]Fallypride, [18F]FPEB, and [18F]FDOPA). Each optimization required a single batch of crude radiopharmaceutical and a few hours. Interestingly, the optimized TLC method provided greater accuracy (compared to other published TLC methods) in determining the product abundance of one radiopharmaceutical studied in more depth ( [18F]Fallypride) and was capable of resolving a comparable number of species as isocratic radio-HPLC. We used the PRISMA-optimized mobile phase for [18F]FPEB in combination with multi-lane radio-TLC techniques to evaluate reaction performance during high-throughput synthesis optimization of [18F]FPEB. The PRISMA methodology, in combination with high-resolution radio-TLC readout, enables a rapid and systematic approach to achieving high-resolution and accurate analysis of radiopharmaceuticals without the need for radio-HPLC.
    Keywords:  PRISMA optimization; Radiochemistry; high-resolution; radio-TLC; radiopharmaceuticals
    DOI:  https://doi.org/10.1016/j.chroma.2022.463656
  30. Anal Chim Acta. 2023 Jan 15. pii: S0003-2670(22)00950-3. [Epub ahead of print]1238 340379
    Review on atmospheric pressure ionization sources for gas chromatography-mass spectrometry. Part II: Current applications.
    Juan F Ayala-Cabrera, Lidia Montero, Sven W Meckelmann, Florian Uteschil, Oliver J Schmitz.
      The application of atmospheric pressure ionization (API) sources in gas chromatography-mass spectrometry (GC-MS) determinations is becoming more popular since they have shown great capabilities to sort out the main drawbacks of vacuum ionization techniques like electron ionization (EI) and chemical ionization (CI). The development of new API techniques and set-ups have grown in the last decades, opening the field of GC-MS to new applications and facing some of the major issues in current analytical methodologies such as the requirement of a compromise between sensitivity and selectivity. Thus, this review is mainly focused on the use of GC-API-MS in different application fields such as food analysis (food safety and food metabolomics), environmental analysis, clinical analysis, drug and pharmaceutical analysis, and petroleomics, among others. The methodologies have been critically reviewed to compare the performance of different API sources and approaches, highlighting the main contributions to overcoming some of the major limitations of the current methodologies as well as the new perspectives that GC-API-MS might open in the different fields.
    Keywords:  Atmospheric pressure ionization; Clinical and drug analysis; Environmental analysis; Food analysis; GC-MS; Petroleomics
    DOI:  https://doi.org/10.1016/j.aca.2022.340379
  31. J Chromatogr A. 2022 Nov 28. pii: S0021-9673(22)00878-0. [Epub ahead of print]1687 463687
    Method development for the acquisition of adsorption isotherm of ion pair reagents Tributylamine and Triethylamine in ion pair chromatography.
    Abdul Haseeb, Maria Rova, Jörgen Samuelsson.
      Tributylamine (TBuA) and triethylamine (TEtA) are the most commonly used ion pair reagents in ion pair chromatography especially for the analysis of oligonucleotides. In order to improve the understanding of the retention and separation mechanism of oligonucleotides in ion pair chromatography, it is important to understand the retention mechanism and the nature of interaction of these ion pair reagents with the stationary phase in the chromatographic column. Adsorption isotherm is helpful in evaluating such interactions, and subsequently predicting the retention mechanism. Alkylamines are very polar molecules which lack suitable chromophore and are commonly present in charged forms. Therefore, their determination and the subsequent acquisition of their adsorption isotherms using traditional liquid chromatography is very difficult. In this study, we first developed an analytical method for the determination of TBuA and TEtA in a typical chromatographic mobile phase (acetonitrile-water) and then used the same method to acquire the adsorption isotherms for tributylammonium acetate (TBuAA) and triethylammonium acetate (TEtAA). This method started with the conversion of the alkylammonium ions to free neutral forms by treating the sample with a strong base, followed by pentane-mediated extraction and finally the analysis of the extracts using gas chromatography-flame ionization detector (GC-FID). This three-step method was validated for parameters like range, linearity, intra-day and inter-day precision and accuracy, limit of detection and limit of quantitation. For the adsorption isotherms, the C18 column was first equilibrated with the solutions having different concentrations of alkylammonium ions and then stripped with eluent devoid of alkylammonium ions. Several stripping eluents were investigated and it was discovered that the eluent requirement could be decreased by the addition of sodium chloride. The effluents from the stripping phase were collected and analyzed using the developed analytical method to acquire the adsorption data. Under the investigated conditions, adsorption of TBuAA and TEtAA showed type III and type I isotherm behavior respectively.
    Keywords:  Adsorption isotherm; Gas chromatography; Liquid chromatography; Tributylamine; Triethylamine
    DOI:  https://doi.org/10.1016/j.chroma.2022.463687
  32. J Sep Sci. 2022 Dec 07.
    Development of two fully automated quick, easy, cheap, effective, rugged, and safe pretreatment methods for the extraction of psychotropic drugs from whole blood samples.
    Takaya Murakami, Reiko Ishimaru, Eriko Minami, Yoshiaki Iwamuro, Naoki Takamura, Aya Torai, Tsutomu Watanabe, Akihiro Miki, Munehiro Katagi, Maiko Kusano, Hitoshi Tsuchihashi, Kei Zaitsu, Satoshi Chinaka.
      Quick, easy, cheap, effective, rugged, and safe extraction strategies are becoming increasingly adopted in various analytical fields to determine drugs in biological specimens. In the present study, we developed two fully automated quick, easy, cheap, effective, rugged, and safe extraction methods based on acetonitrile salting-out assisted liquid-liquid extraction (method 1) and acetonitrile salting-out assisted liquid-liquid extraction followed by dispersive solid-phase extraction (method 2) using a commercially available automated liquid-liquid extraction system. We applied these methods to the extraction of 14 psychotropic drugs (11 benzodiazepines and carbamazepine, quetiapine, and zolpidem) from whole blood samples. Both methods prior to liquid chromatography-tandem mass spectrometry analysis exhibited high linearity of calibration curves (correlation coefficients, >0.9997), ppt level detection sensitivities, and satisfactory precisions (<8.6% relative standard deviation), accuracies (within ±16% relative error), and matrix effects (81%-111%). Method 1 provided higher recovery rates (80%-91%) than method 2 (72%-86%), whereas method 2 provided higher detection sensitivities (limits of detection, 0.003-0.094 ng/mL) than method 1 (0.025-0.47 ng/mL) owing to the effectiveness of its dispersive solid-phase extraction cleanup step. These fully automated extraction methods realize reliable, labor-saving, user-friendly, and hygienic extraction of target analytes from whole blood samples. This article is protected by copyright. All rights reserved.
    Keywords:  and safe extraction; cheap; easy; effective; fully automated pretreatment; liquid chromatography-tandem mass spectrometry; psychotropic drug; quick; rugged; whole blood
    DOI:  https://doi.org/10.1002/jssc.202200681
  33. J Biosci Bioeng. 2022 Dec 06. pii: S1389-1723(22)00339-5. [Epub ahead of print]
    Lipidome variation of industrial Saccharomyces cerevisiae strains analyzed by LC-QTOF/MS-based untargeted lipidomics.
    Shuka Komori, Nobuyuki Okahashi, Junko Iida, Fumio Matsuda.
      Although various yeast strains used in the food industry have been characterized by multilayer analysis, knowledge of the variation of lipid profiles involved in fermentation characteristics and stress tolerance remains in its infancy. In this study, untargeted lipidomics was applied to 10 yeast strains, including laboratory, baker's, wine, and sake yeasts, which exhibit distinct fermentation phenotypes, to obtain a comprehensive overview of the yeast lipidome. The relative standard deviation (RSD) in the abundance of the 352 identified lipid molecular species was investigated to reveal the specific and common lipids. Lipids containing very long-chain fatty acids and hydroxy long-chain fatty acids showed relatively large RSD, whereas lipids containing acyl chains, which are commonly found in yeast, such as C16-C18, showed less RSD among the 10 strains. Furthermore, principal component analysis of lipid profiles showed similar trends among industrial yeast strains. As lipids are involved in yeast phenotypes, including stress tolerance and fermentation characteristics, correlation analysis was performed with lipid abundance and phenotypes. The results revealed that molecular species with a high RSD in abundance among the 10 strains were correlated with specific stress tolerance and fermentation phenotypes.
    Keywords:  Industrial yeast; Liquid chromatography-quadrupole time-of-flight/mass spectrometry; Saccharomyces cerevisiae; Stress tolerance; Untargeted lipidomics
    DOI:  https://doi.org/10.1016/j.jbiosc.2022.10.011
  34. Anal Bioanal Chem. 2022 Dec 09.
    Synthesis of emerging cathinones and validation of a SPE GC-MS method for their simultaneous quantification in blood.
    Sara Júlio, Raquel A Ferro, Susana Santos, Andrea Alexandre, Maria João Caldeira, João Franco, Mário Barroso, Helena Gaspar.
      Over the past 15 years, synthetic cathinones have emerged as an important class of new psychoactive substances (NPS) worldwide. The proliferation of these psychostimulants and their sought-after effects among recreational drug users pose a serious threat to public health and enormous challenges to forensic laboratories. For forensic institutions, it is essential to be one step ahead of covert laboratories, foreseeing the structural changes possible to introduce in the core skeleton of cathinones while maintaining their stimulating activity. In this manner, it is feasible to equip themselves with standards of possible new cathinones and validated analytical methods for their qualitative and quantitative detection. Therefore, the aim of the work herein described was to synthesize emerging cathinones based on the evolving patterns in the illicit drug market, and to develop an analytical method for their accurate determination in forensic situations. Five so far unreported cathinones [4'-methyl-N-dimethylbuphedrone (4-MDMB), 4'-methyl-N-ethylbuphedrone (4-MNEB), 4'-methyl-N-dimethylpentedrone (4-MDMP), 4'-methyl-N-dimethylhexedrone (4-MDMH), and 4'-methyl-N-diethylbuphedrone (4-MDEB)] and a sixth one, 4'-methyl-N-ethylpentedrone, already reported to EMCDDA and also known as 4-MEAP, were synthesized and fully characterized by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). An analytical method for the simultaneous quantification of these cathinones in blood, using solid phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) was developed and validated. The results prove that this methodology is selective, linear, precise, and accurate. For all target cathinones, the extraction efficiency was higher than 73%, linearity was observed in the range of 10 (lower limit of quantification, LLOQ) to 800 ng/mL, with coefficients of determination higher than 0.99, and the limits of detection (LODs) were 5 ng/mL for all target cathinones. The stability of these cathinones in blood matrices is dependent on the storage conditions; 4-MNEB is the most stable compound and 4-MDMH is the least stable compound. The low limits obtained allow the detection of the compounds in situations where they are involved, even if present at low concentrations.
    Keywords:  Blood; GC–MS; NMR; NPS; Synthetic cathinones
    DOI:  https://doi.org/10.1007/s00216-022-04440-6
  35. J Chromatogr Sci. 2022 Dec 05. pii: bmac096. [Epub ahead of print]
    Immunopurification Reagents and Their Application in Biologics and Biomarker Quantitation Using LC-MS/MS in Drug Discovery.
    Shashyendra Singh Gautam, Sheelendra Pratap Singh.
      The LC-MS/MS technology is one of the most utilized bio-analytical tools owing to its advantage of selectivity, sensitivity and multitasking. The advent of novel biological therapies and increasing demand for protein biomarker identification and quantitation have put the LC-MS/MS technology at the forefront. The questions which are been posed to the LC-MS/MS scientist are complex. The complexity of the question increases further with the matrices in which these questions need to be answered. To bring down the complexity of the analysis, LC-MS/MS technology is utilizing the immunopurification (IP) technique as the new sample preparation technique. The IP reagents are the most common reagents which are used to decrease the matrices' complexity and allow the LC-MS/MS system to reach greater sensitivity. The utilization of these reagents is increasing every day, but the proper utilization of these reagents is still unknown to the common analyst in drug discovery. The present review throws light on the utilization aspect of these reagents, as we have classified these reagents on basis of their utilization, which will allow the readers to gain an understanding of these reagents. This review will also talk about the merits and the demerits of each approach and the current understanding of utilizing these reagents.
    DOI:  https://doi.org/10.1093/chromsci/bmac096
  36. Adv Pharmacol Pharm Sci. 2022 ;2022 3133640
    Sweat Cortisol and Cortisone Determination in Healthy Adults: UHPLC-MS/MS Assay Validation and Clinical Application.
    Syed N Alvi, Kafa Abuhdeeb, Muhammad M Hammami.
      A simple and effective ultra-high-performance liquid chromatography assay linked to tandem mass spectrometry (UHPLC-MS/MS) for measuring cortisol and cortisone levels in human sweat has been developed and validated. A noninvasive world standard sweat collecting equipment was utilized to collect samples. The samples were analyzed using an Atlantis dC18 (2.1 × 100 mm, 3 μm) column with a 2 mM ammonium acetate and acetonitrile (1 : 1, v : v) mobile phase. In an isocratic condition, the mobile phase was delivered at a flow rate of 0.3 ml/minute. A positive electrospray ionization interface with multiple-reaction monitoring mode was used to provide simultaneous quantification of cortisol, cortisone, and internal standard at transitions of 363.11 to 121.00, 361.18 to 163.11, and 367.19 to 121.24, respectively. The method was validated for cortisol and cortisone determination over a concentration range of 0.5-50 ng/mL The detection limits for cortisol and cortisone in human sweat were 0.3 and 0.2 ng/ml, respectively. The interday coefficients of variation of cortisol and cortisone were ≤8.5% and ≤10.01%, whereas bias was in the range from -7.9% to 2.1% and from -4.3% to 3.0%, respectively. The assay was successfully applied to evaluate the cortisol-to-cortisone ratio in sweat samples collected from healthy adult volunteers.
    DOI:  https://doi.org/10.1155/2022/3133640
  37. J Pharm Sci. 2022 Nov 30. pii: S0022-3549(22)00536-6. [Epub ahead of print]
    A GC-MS/MS method for trace level quantification of six nitrosamines impurities (NDMA, NDEA, NEIPA, NDIPA, NDPA, and NDBA) in commercially used organic solvents: Dichloromethane, Ethyl acetate, Toluene, and o-Xylene.
    Eswara Raju Kosuri, Mayank Bhanti, Mrunal Jaywant, Mark Han, Xiaochun Wang, Marcus Obeng.
      Nitrosamines, the probable carcinogens have been reported with Angiotensin II Receptor Blocker (ARB) drugs, Ranitidine, and other medicines. Solvents play a vital role in the pharmaceutical industry in the separation, purification, and cleaning process for manufacturing APIs and drug products. According to the FDA and EMA, solvents used in the drug manufacturing process are potential root causes of Nitrosamine impurities. Hence, monitoring nitrosamines in solvents is an essential step for manufacturers. A sensitive direct injection GC-MS/MS, an essential analytical tool for low-level nitrosamine quantification in solvents, was developed by utilizing multiple reactions monitoring mode (MRM) for the simultaneous determination of six nitrosamines, namely, NDMA, NDEA, NEIPA, NDIPA, NDPA and NDBA in common solvents such as dichloromethane, ethyl acetate, toluene, and o-xylene. NDMA-d6 was used as an internal standard. The FDA reported a combined direct injection method for nitrosamine impurity assay by GC-MS/MS, which had several challenges for commercial-grade solvents in terms of interferences and resolution of unknown impurities and nitrosamine peaks. A novel method was developed to optimize the critical parameters of GC-MS/MS according to the solvent samples. The method validation was performed through the following parameters, sensitivity, linearity, accuracy, precision, specificity, and stability. The quantification of nitrosamines in commercial-grade solvents ranged from 100 ppb to 8000 ppb with respect to the sample concentration of 25 mg/mL with good sensitivity in LOQ level. The quantification ranged from 5 ppb (for NDMA, NDEA, NEIPA, NDIPA, NDPA) and 13 ppb (NDBA) to 2000 ppb with respect to the sample concentration of 100 mg/mL for analytical grade solvents with good sensitivity in the proposed method. Hence it will be useful to quantify the low-level nitrosamines in commercial-grade solvents as well as analytical-grade solvents.
    Keywords:  Angiotensin-II-receptor blockers; GC-MS/MS; Nitrosamine; Solvents; Triple quadrupole mass spectrometer; Validation
    DOI:  https://doi.org/10.1016/j.xphs.2022.11.024
  38. Anal Chem. 2022 Dec 09.
    "Organ-in-a-Column" Coupled On-line with Liquid Chromatography-Mass Spectrometry.
    Stian Kogler, Aleksandra Aizenshtadt, Sean Harrison, Frøydis Sved Skottvoll, Henriette Engen Berg, Shadab Abadpour, Hanne Scholz, Gareth Sullivan, Bernd Thiede, Elsa Lundanes, Inger Lise Bogen, Stefan Krauss, Hanne Røberg-Larsen, Steven Ray Wilson.
      Organoids, i.e., laboratory-grown organ models developed from stem cells, are emerging tools for studying organ physiology, disease modeling, and drug development. On-line analysis of organoids with mass spectrometry would provide analytical versatility and automation. To achieve these features with robust hardware, we have loaded liquid chromatography column housings with induced pluripotent stem cell (iPSC) derived liver organoids and coupled the "organ-in-a-column" units on-line with liquid chromatography-mass spectrometry (LC-MS). Liver organoids were coloaded with glass beads to achieve an even distribution of organoids throughout the column while preventing clogging. The liver organoids were interrogated "on column" with heroin, followed by on-line monitoring of the drug's phase 1 metabolism. Enzymatic metabolism of heroin produced in the "organ-in-a-column" units was detected and monitored using a triple quadrupole MS instrument, serving as a proof-of-concept for on-line coupling of liver organoids and mass spectrometry. Taken together, the technology allows direct integration of liver organoids with LC-MS, allowing selective and automated tracking of drug metabolism over time.
    DOI:  https://doi.org/10.1021/acs.analchem.2c04530
  39. Mar Pollut Bull. 2022 Nov 30. pii: S0025-326X(22)01051-7. [Epub ahead of print]186 114369
    A stable isotope assay with 13C-labeled polyethylene to investigate plastic mineralization mediated by Rhodococcus ruber.
    Maaike Goudriaan, Victor Hernando Morales, Marcel T J van der Meer, Anchelique Mets, Rachel T Ndhlovu, Johan van Heerwaarden, Sina Simon, Verena B Heuer, Kai-Uwe Hinrichs, Helge Niemann.
      Methods that unambiguously prove microbial plastic degradation and allow for quantification of degradation rates are necessary to constrain the influence of microbial degradation on the marine plastic budget. We developed an assay based on stable isotope tracer techniques to determine microbial plastic mineralization rates in liquid medium on a lab scale. For the experiments, 13C-labeled polyethylene (13C-PE) particles (irradiated with UV-light to mimic exposure of floating plastic to sunlight) were incubated in liquid medium with Rhodococcus ruber as a model organism for proof of principle. The transfer of 13C from 13C-PE into the gaseous and dissolved CO2 pools translated to microbially mediated mineralization rates of up to 1.2 % yr-1 of the added PE. After incubation, we also found highly 13C-enriched membrane fatty acids of R. ruber including compounds involved in cellular stress responses. We demonstrated that isotope tracer techniques are a valuable tool to detect and quantify microbial plastic degradation.
    Keywords:  Compound specific isotope analysis; Membrane lipids; Microbial plastic degradation; Polyethylene biodegradation rates; Rhodococcus ruber; Stable isotope probing
    DOI:  https://doi.org/10.1016/j.marpolbul.2022.114369
  40. Crit Rev Anal Chem. 2022 Dec 07. 1-16
    Quantification of Monoamine Neurotransmitter Metabolites and Cofactors in Cerebrospinal Fluid: State-of-the-Art.
    Ayoub Boulghobra, Myriam Bonose.
      Inborn errors of monoamine neurotransmitter metabolism are rare diseases characterized by nonspecific neurological symptoms. These symptoms appear in early childhood and correspond to movement disorders, epilepsy, sleep disorders and/or mental disability. Cerebrospinal fluid biomarkers have been identified and validated to allow specific diagnosis of these diseases. Biomarkers of inborn errors of monoamine neurotransmitter metabolites are divided in two groups: monoamine neurotransmitter metabolites and pterins. Biomarkers quantification in cerebrospinal fluid is based on high-performance liquid chromatography separation coupled to electrochemical detection, fluorescence detection, or mass spectrometry. The following article reviews the advances in the proposed routine methods for the measurement of these analytes in cerebrospinal fluid. The purpose of this review is to compare the various proposed methods in terms of sample preparation, chromatographic conditions and detection modes. Despite the broad range of proposed methods, quantification of inborn errors of monoamine neurotransmitter biomarkers remains a great challenge, given the complexity of biological fluids and the low amounts of analytes that are present in cerebrospinal fluid.
    Keywords:  Biomarkers; CSF; HPLC; monoamine neurotransmitter metabolites; pterins
    DOI:  https://doi.org/10.1080/10408347.2022.2151833
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