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The article discusses the use of metabolomics in the diagnosis of glaucoma. Topics mentioned include the definition of metabolomics, a description of metabolomics workflow, the list of high-frequency metabolics related to open angle glaucoma and the use of mass spectroscopy and nuclear magnetic resonance spectroscopy to study metabolomics.

Enumerable types of gene therapies are collectively one of the fastest-growing areas of biopharmaceutical products today. Gene therapies are generally defined as treatments, perhaps even cures, for diseases through the transfer of genetic material to host cells. The analytical technologies that exist to characterize these novel therapies are rapidly advancing. In this column, we will briefly present some of the basic concepts related to this novel product class, specifically related to formulation and delivery, focusing on adeno-associated virus (AAV) formulations. We will then briefly discuss the analytical technologies and approaches most commonly used to characterize these products, specifically on the characterization of AAV-related products. We will briefly discuss what many consider the gold standard in analytical tools, analytical ultracentrifugation (AUC), and then specifically discuss liquid chromatography-mass spectrometry (LC-MS) tools and methods (such as the multi-attribute method, MAM) that are becoming more commonly used in characterization. [ABSTRACT FROM AUTHOR]

The article discusses highlights from the 51st International Symposium on High Performance Liquid Phase Separations and Related Techniques (HPLC 2023). Topics include a discussion on the importance of the high performance liquid chromatography (HPLC) technique for biotherapeutics, presentation of a group's work on developing a platform of chromatographic methods in fully characterizing protein glycoforms, and research on suitable greener alternative solvents for use in chromatography.

The article focuses on the evaluation of shifted-excitation Raman difference spectroscopy (SERDS) and its comparison to ordinary portable Raman spectroscopy for identifying seized drugs. It study explores how SERDS, which reduces fluorescence interference, and traditional Raman spectroscopy perform in terms of detection rate and matching accuracy in analyzing seized drug samples.

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with a dual electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) source was developed for analyzing 102 pesticides and five mycotoxins that are regulated by the state of Colorado in hemp. The limit of quantitation (LOQ) of the 102 pesticides and five mycotoxins met Colorado state action limit requirements for these analytes in a hemp matrix. For this study, 88 out of 102 pesticides and all five mycotoxins were analyzed using LC-MS/MS with an ESI source, whereas the remaining 14 pesticides were determined using LC-MS/MS with an APCI source. A simple, fast, green, and cheap acetonitrile solvent extraction method was used to extract the pesticides and mycotoxins from the hemp matrix with good extraction efficiency in the range of 80-120%. A hemp matrix is challenging and causes matrix effects such as ion suppression or enhancement. We optimized the LC method and added 30 internal standards to reduce and compensate for these matrix effects to obtain method accuracy in the range of 70-120%. The ionization mechanism of nonpolar pesticides (normally analyzed by gas chromatography-tandem mass spectrometry [GC-MS/MS]) with an APCI ion source was elucidated. [ABSTRACT FROM AUTHOR]

Multi-attribute methods (MAMs) are becoming increasingly popular for their ability to analyze multiple critical quality attributes (CQA) in a single workflow. This capability becomes particularly attractive for a product class such as monoclonal antibodies, which are large and complex, and have many CQAs that need to be monitored and controlled during their manufacturing so as to deliver consistent product quality. In an earlier installment, we discussed the role of liquid chromatography and mass spectrometry in MAMs. In this article, we focus on intact mass analysis-based multi-attribute methods (iMAMs), a suitable alternative that can complement standard MAMs or be used when there is a need for rapid turnaround and monitoring of only a limited number of CQAs. Multiple case studies are presented to elucidate this concept. [ABSTRACT FROM AUTHOR]

The article discusses possible pitfalls in the use of liquid chromatography-mass spectrometry (LC-MS) for proteomics applications and tips for avoiding them. Topics covered include issues on contamination, polymers, urea, residual salts, water quality, and keratins, and optimizing electrospray source voltages in nanoLC-ESI-MS. Also noted is the importance of step details leading to LC-MS data acquisition, like in sample preparation chemistries, and in optimization of instrument parameters.

The article discusses research which analyzed approximately 400 pesticides extracted from black tea via liquid chromatography-tandem mass spectrometry (LC-MS/MS) as demonstrated by simple solvent extraction sample preparation and atmospheric pressure chemical ionization (APCI) to improve analyte coverage. The study evaluated the accuracy, precision and limits of quantification of the methods and investigated matrix effects to explore method performance between black tea, chamonile and catnip.

Per- and polyfluoroalkyl substances (PFAS) are a large group of anthropogenic chemicals that have been applied in a wide range of industrial, commercial, and domestic products since the 1950s. Because of their toxicity, persistence, and bioaccumulation potential, PFAS have become global environmental pollutants. Besides the environment, the food chain represents another source of exposure, and the risk to consumers related to the presence of PFAS in foods has recently become of increased interest. In this respect, whole milk, infant formula, and ingredients used in infant formula production represent important foodstuffs that require sensitive methods with reporting limits at low parts per billion (ppb) levels or lower for multiple PFAS. This article summarizes optimization experiments and the validation of a complete workflow, including sample preparation and a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of 16 priority PFAS analytes listed by the U.S. Food and Drug Administration (FDA). [ABSTRACT FROM AUTHOR]

An ultrahigh-pressure liquid chromatography-mass spectrometry (UHPLC-MS) research prototype instrument was built to improve the resolution power and the usability of conventional LC-MS hyphenated instruments for routine analyses in pharmaceutical applications. The improved characteristics of this UHPLC-MS system include: 1) the dramatic reduction of post-column sample dispersion; 2) the adoption of vacuum jacketed columns (VJC) for the reduction of undesirable radial temperature gradients across the column diameter; and 3) the presence of a column outlet end nut heater to refocus the distorted peaks prior to analyte ionization. The benefits of each of these added features are analyzed with a rigorous approach from a peak broadening perspective. A 2x improvement in peak capacities recorded with this prototype UHPLC-MS system compared to a standard system (Acquity UHPLC I-class/Xevo TQ-S) is illustrated for the gradient separation of seven small pharmaceutical compounds using a 2.1 mm x 100 mm column packed with sub-2-μm core-shell particles (1.6 μm Acquity UHPLC Cortecs C18 column). [ABSTRACT FROM AUTHOR]

Identification, monitoring, and, more importantly, linkage of critical quality attributes (CQAs) in processing parameters in a biopharmaceutical product is required to ensure the quality and manufacturing consistency of the product, but also its safety and efficacy during clinical and commercial development. Recently, bottom-up and middle-up liquid chromatography–mass spectrometry (LC–MS) characterization strategies using immobilized enzyme reactors (IMERs) in combination with multidimensional liquid chromatography coupled with high-resolution MS (MDLC–HRMS), as well as sophisticated software solutions, have been added to the analytical toolbox. These strategies not only allow faster characterization of post-translational modifications (PTMs) present in biotherapeutic proteins but also have the potential to provide a fully automated and unified bottom-up, middle-up, and intact LC–MS characterization approach. [ABSTRACT FROM AUTHOR]

Immobilized enzyme reactors (IMERs) are a powerful and essential part of multidimensional liquid chromatography–tandem mass spectrometry (MDLC–MS/MS) approaches that enable online identification, characterization, and quantification of post-translational modifications of therapeutic antibodies. This review gives an overview of commercially available and selected trypsin IMERs in regard to their application in LC-based and automated sample preparation. Additionally, we address the challenges of IMER application in online systems and the advantages of self-made IMERs. [ABSTRACT FROM AUTHOR]

Fipronil is a widely used insecticide. Exposure of humans to fipronil can cause harmful health effects. The aim of the present work is to develop a liquid chromatography--tandem mass spectrometry (LC--MS/MS) method for the rapid detection of fipronil and its metabolites in eggs and environmental matrices (soil, feed, and chicken feed bags). Solvent extraction was performed with a mixture including water, acetonitrile, and sodium chloride, followed by purification using a solid-phase extraction column. The LC separation was accomplished on a C18 column, and the detection was performed with a triple quadrupole mass spectrometer using electrospray ionization in multiple reaction monitoring (MRM) mode. The results showed a good linear relationship between fipronil and its metabolites in the range of 0.01 to 20 ng/mL, and the linear correlation coefficients (R²) were all greater than 0.999. The detection and quantification limits of the method for all analytes were 0.01 and 0.05 ng/mL, respectively. The precision expressed as coefficients of variation (n = 3) for assay of fipronil and its metabolites ranged from 8.4% to 13.2% at three levels (0.1 ng/mL, 1 ng/mL, and 10 ng/mL). The recoveries ranged from 81.3% to ~119.5%. Finally, we successfully employed the method to a case of fipronil contamination, and found residues of fipronil and its metabolites in eggs and the environmental matrix. [ABSTRACT FROM AUTHOR]

In some countries, quinoxaline 1,4-dioxide (QdNO) has been banned as a feed additive because of its potential genotoxicity. To assess the residue levels in animal tissues, an ultrahigh-pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed to determine five QdNOs and its eight main metabolites in swine liver. The samples were simply extracted by 0.1% formic acid in acetonitrile (4+6, v/v) after being acidified with 3 mol/L of 0.1% hydrochloric acid, and purified using a HLB cartridge. The UHPLC-MS/MS provided good linearity to the peak area, with the linear correlation coefficients of over 0.98 within the concentration range of 5-500 µg/L. The limit of detection (LOD) was 0.30-2.51 µg/kg, and the limit of quantification (LOQ) was 1.10-8.37 µg/kg for the 13 target compounds. When the target compounds spiked at 10, 100, and 500 µg/kg, the recoveries ranged from 79.8 to 96.5%. This method is suitable for the residual determination of real samples. [ABSTRACT FROM AUTHOR]

This article is the second of a series of four white papers on the bioanalysis of small-molecule drugs and metabolites by liquid chromatography-mass spectrometry (LC-MS). Part 1 was an overview of the fundamentals and regulations. This installment, part 2, is on sample preparation. Part 3 will cover method development, optimization, and best practices, and part 4 discusses method validation for regulated bioanalysis. This section provides an overview of sample preparation fundamentals, best practices, and modern trends. A sample preparation method development case study illustrates these practices and concepts. [ABSTRACT FROM AUTHOR]

In the process of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay development for two antimicrobial drugs using their stable isotope-labeled (SIL) analogues as internal standards to correct for matrix-ion suppression effects, an unusually large scatter of data was observed. A systematic observation revealed that the analytes and their SIL analogues (internal standards) were not completely coeluted; therefore, the analytes were not experiencing matrix effects similarly. When a column with lower resolution ability was used to achieve complete overlapping of the analyte and internal standard peaks, the scatter of LC-MS/MS data was minimized, indicating that the maximum correction of matrix effects by internal standards occurs when they are completely coeluted with the analytes. This study highlights the importance of ensuring complete overlapping of analyte and internal standard peaks in eliminating matrix effects when using SIL analogues as internal standards in LC-MS. [ABSTRACT FROM AUTHOR]

This article is the first of four on the bioanalysis of small-molecule drugs and metabolites by liquid chromatography-mass spectrometry (LC-MS). In this article, we provide an overview of the fundamentals, workflow, regulations, and modern trends on these quantitative assays. [ABSTRACT FROM AUTHOR]

Cleaning verification (CV) is a critical step in the pharmaceutical manufacturing process to ensure unadulterated products are released to the patient. Recent advances in chromatographic CV techniques, such as liquid chromatography-ultraviolet detection (LC-UV), liquid chromatography-mass spectrometry (LC-MS), liquid chromatography with charged aerosol detection (LC-CAD), and spectrometric methods for small molecule pharmaceuticals, are summarized and compared based on their sensitivity, specificity, robustness, versatility, and throughput. A CV workflow utilizing the abovementioned methods and visual verification is proposed. [ABSTRACT FROM AUTHOR]

This article describes challenges and opportunities in separation science in the rapidly emerging field of RNA modifications. Recent advances in sample preparation have permitted the analysis of RNA modifications in single cells by liquid chromatography--mass spectrometry (LC--MS). The sample handling and microextraction methods described here pave the way for new insights into the function of these unusual molecules in the brain and biological systems. [ABSTRACT FROM AUTHOR]

Multidimensional liquid chromatography, coupled to mass spectrometry (MDLC-MS) is a powerful tool for the characterization of complex biopharmaceutical drug modalities, from antibody-drug conjugates to nuclear acid therapuetics like antisense oligonucleotides and small interfering RNA. [ABSTRACT FROM AUTHOR]

Alkaloids are the main bioactive ingredients derived from menispermi rhizoma (MR), which is often used in traditional Chinese medicine. However, simultaneous determination of different types of alkaloids in urine has not been reported. A sensitive, rapid, and efficient ultrahigh-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for rapid quantification of five major bioactive alkaloids (covering three different types) in rat urine has been established. Extraction of five alkaloids from rat urine was performed with acetonitrile precipitation. The separation was carried out on a C18 column, and the detection was performed with positive electrospray ionization (ESI) MS in multiple reaction monitoring (MRM) mode. The method was fully validated and successfully applied to a urinary excretion study of five alkaloids in rats after they were given an oral dose of MR extract. It is the first time that the urinary excretion profiles of dauricoside, acutumine, and acutumidine in rats has been reported. The results obtained lay the foundation for the clinical application and safety evaluation of MR. [ABSTRACT FROM AUTHOR]

The article offers information on electrospray ionization (ESI), is used for the analysis of a broad variety of compounds, ranging from polar to moderately nonpolar. Topic include choosing the appropriate ionization source, liquid chromatography with tandem mass spectrometry (LC–MS/MS) can be used for the detection of trace levels of contaminants, such as antibiotics and Endocrine Disrupting Compounds (EDCs) from environmental samples.

Because of advances in the fundamental understanding of gene therapy treatments and the 2017 regulatory approval of a recombinant adeno-associated viral therapy (rAAV), interest in developing rAAV-based therapies has increased. However, for patients worldwide to truly benefit from these therapies, significant improvements in the efficacy and manufacturing efficiency of rAAV are essential. We have recently seen substantial increases of inquiries regarding liquid chromatography (LC) and liquid chromatography-mass spectrometry (LC-MS) methods for the characterization and analysis of rAAV from scientists who are supporting advancements in product development. This edition of "Column Watch" highlights selected LC and LC-MS methods that can be applied to the analysis of these complex products. [ABSTRACT FROM AUTHOR]

The article offers information on Modern UV-absorbance detectors used for LC exhibit a linear response over an analyze concentration range of more than four orders of magnitude (powers of ten). Topic include the characteristic of CAD, though, is that it will also "see" impurities in the mobile phase, or interferences in the sample, that would otherwise not be detected by UV-absorbance detectors if they do not contain chromophores.

Tobacco-specific nitrosamines are important carcinogens in tobacco products. This article describes a fast, sensitive, selective, and robust method for analysis of these compounds in various tobacco samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The separation of analytes from matrix interfering components was performed using a C18 column with simple LC-MS mobile phases. To minimize sample matrix effects on each analyte, a separate internal standard was used for each analyte. Two MS/MS ion pairs were used for each analyte for analyte confirmation and quantification, further enhancing the method's selectivity and accuracy. The method was validated using different tobacco matrices. [ABSTRACT FROM AUTHOR]

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with a dual electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI) source was developed for analysis of 66 pesticides and 5 mycotoxins regulated by the State of California in medium-chain triglyceride (MCT) oil cannabis tinctures. The limits of quantitation (LOQs) of all of the pesticides and mycotoxins were well below California state action limits of these analytes in cannabis-based non-inhalable or edible products. A total of 62 (out of 66) pesticides and 5 mycotoxins were analyzed using LC-MS/MS with an ESI source, and the remaining 4 pesticides were determined using LC-MS/MS with an APCI source. A simple, fast, and cheap acetonitrile solvent extraction method was used for sample preparation to get good recovery and achieve high throughput for this analysis. For late-eluted analytes, a number of internal standards were used to compensate for ion suppression effects from the hydrophobic matrix. [ABSTRACT FROM AUTHOR]

A single laboratory validation study (SLV) was performed using an ultrahigh-pressure liquid chromatography (UHPLC) for the determination of coenzyme Q10 in a variety of formulations (raw materials, soft gel capsules, and in-process blend). The authors first developed an efficient extraction procedure to obtain coenzyme Q10 from finished products, and then used UHPLC to analyze the ingredient. Compared to the traditional highperformance liquid chromatography (HPLC) method, the UHPLC method reduced the total run time from 15 min to less than 2 min. The total amount of solvent usage was also reduced by 90%, which is a big contribution to green chemistry. The established UHPLC method exhibits good linearity, reproducibility, accuracy, recovery, and specificity. The limit of detection (LOD) and limit of quantification (LOQ) were also captured in the study, and have been proven suitable for monitoring the coenzyme Q10 in complex matrices. [ABSTRACT FROM AUTHOR]

The article offers information on the methods and considerations for handling complex samples. Topics include the measurement of ethanol content in blood samples being great example of the technique and requires no cleanup of the matrix prior to injection, the supercritical fluid chromatography (SFC) continues to re-emerge for use over a wide range of sample, and the liquid chromatography (LC) being imperative for samples with higher molecular weight analytes.

The article discusses ice concentration linked with extractive stirrer (ICECLES) provides highly efficient isolation of trace compounds from aqueous samples. It mentions that water in the soda is freezing, the carbon dioxide is being forced out of the water, and building up so much pressure that an explosion occurs. It also mentions history of freeze concentration in analytical chemistry.

The article discusses technical challenges encountered during chromatographic method transfers to pharmaceutical manufacturing sites. It mentions that genotoxic impurities has resulted in analytical control strategies increasingly utilizing analytical detection techniques outside of traditional quality control-friendly liquid chromatography–ultraviolet and gas chromatography–flame ionization detector instruments.

Research tools that can decipher protein-protein interactions and binding interface contact points can aid in the successful development of biotherapeutics. Hydroxyl radical footprinting-mass spectrometry (HRF-MS) technologies are being developed as tools for deciphering protein-protein interactions. We have demonstrated the utility of using fast photochemical oxidation of proteins (FPOP) as an HRF-MS technology for biotherapeutic protein structural characterization and analysis of protein-protein interfaces; monoclonal antibody (mAb) epitope mapping has also been demonstrated using this technique. However, the postlabeling workflow that utilizes offline protein digestion and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis is labor intensive and time consuming, and has significant sample consumption. In the present work, we demonstrate the potential of multidimensional online peptide mapping analysis (reduction, tryptic digestion, and separation) as a strategy for improving our postlabeling workflow for proteinprotein interactions. The proof-of-concept studies were performed using a Fab antibody fragment and its antigen binding partner. [ABSTRACT FROM AUTHOR]

Peptide mapping by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an essential analytical tool for the characterization of biotherapeutics, such as for the identification and quantification of post-translational modifications, including oxidation. Therefore, is it crucial that the LC-MS system is performing under optimal conditions, ensuring reproducible and accurate quantitative information. A system suitability test is usually performed prior to sample analysis to confirm that the sample preparation and instrument performance are adequate and running as expected. Induced in-source oxidation is a known phenomenon associated with the electrospray process, and can be discriminated from relevant sample oxidation. On-column methionine oxidation can also take place during LC-MS/MS peptide mapping analysis of antibody-based biotherapeutics over long-term column use. This article describes how the monitoring of on-column methionine oxidation as part of system suitability testing can be used to control unintended on-column methionine oxidation of biotherapeutics. This approach minimizes the risk of measuring oxidative artifacts, and helps generate high quality data to provide reliable quantitative information about product-related heterogeneities. [ABSTRACT FROM AUTHOR]

An interview with Jim Garvey, the Head of Food Chemistry is presented. Topics include spoke about how his group develops methods, including those using high-resolution accurate mass-mass spectrometry (HRAM-MS), to meet ever-changing demands in pesticide analysis; mentions that monitoring laboratories have a different approach to increase in instrument sensitivity; and also mentions about his next steps in pesticide analysis overall.

Environmental contaminants can affect human and animal health and are thus an issue of concern. Anthony Provatas is a Research Professor and the Organics Laboratory Manager at the University of Connecticut in the Center for Environmental Sciences and Engineering (CESE) of the Institute of the Environment; he is also Program Chair and Board Member of the Eastern Analytical Symposium (EAS). His research has been focused on the effects of contaminants on human health. We recently spoke to him about his work using ultrahigh-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and UHPLC-quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS) to analyze the presence of per- and polyfluoroalkyl substances (PFAS) in the environment, particularly in foods. [ABSTRACT FROM AUTHOR]

Glycosylation accounts for the highest abundance of post-translational modifications (PTMs), since more than 50% of mammalian proteins are glycosylated. Recently, glycosylation has attracted much interest due to its versatile biological functions, including cell signaling, cell-cell interaction, cell adhesion, and protein stabilization. Aberrant glycosylation has been demonstrated to be associated with the development of diseases. Thus, many glycomics studies have been performed to investigate glycan expression alterations in biological processes. Furthermore, glycan isomers have also been reported to be involved in many diseases, a fact that demands more in-depth study of isomeric glycomics. However, most research efforts to date have focused on glycan profiles. Glycan isomer expressions have not been well studied, due to inefficient separation and structural identification techniques. Fortunately, with the development of novel separation techniques and liquid chromatography-mass spectrometry (LC-MS) based glycan isomer identification strategies, new efforts have been made to investigate the glycan isomers in various diseases. In this paper, we review the recent advances of several isomeric separation techniques of both N- and O-glycans, along with recent clinical glycan isomer biomarker discoveries, to provide an overview of isomeric glycomics for the benefit of further studies. [ABSTRACT FROM AUTHOR]

Biotherapeutics are a growing class of drugs that need extensive characterization of heterogeneities that are acquired during their manufacturing, storage, and distribution. Liquid chromatography-mass spectrometry (LC-MS) is widely considered a gold standard for characterization of biopharmaceuticals. Capillary electrophoresis (CE) offers a promising alternative to high performance liquid chromatography (HPLC), but one of the challenges that has often been cited is the difficulty in coupling it with MS. In this article, we discuss the coupling of CE with MS, advantages of CE-MS over LC-MS, some recent applications of the technology in the field of biotherapeutics, and the various parameters that are important to obtain a stable CE-MS profile. [ABSTRACT FROM AUTHOR]

An interview with Technical University of Munich professor Thomas Letzel is presented. When asked about adequate analytical techniques for handling water analysis challenges, Letzel mentions his satisfaction on their availability. He also notes his expertise in chromatography as well as points out his suggestions for liquid chromatography-mass spectrometry (LC-MS).

The article focuses on the role of column chemistry in developing highly selective high-performance liquid chromatography (HPLC) methods for peptides. Topics discussed include significance of monoclonal antibodies (mAbs) in biotherapeutics, peptide mapping by using liquid chromatography–mass spectrometry (LCMS), and chart showing list of peptides used in kappa-kappa study.

Liquid chromatography-mass spectrometry (LC-MS) has become the preferred analytical technique for many challenging assays based on its selectivity, sensitivity, and broad applicability to compounds of varying polarity. Despite the advantages of the technique, the complexity of LC-MS systems often leaves analysts struggling to meet method detection limits. In this installment of "Column Watch," several strategies are discussed to improve method sensitivity through the reduction of contaminants, the careful selection of LC method conditions, and the optimization of MS interface settings. By understanding the relationship between these parameters and ionization efficiency, analysts can enhance their signal-to-noise ratio and realize the hidden potential of the LC-MS technique. [ABSTRACT FROM AUTHOR]

The article offers the author's insights on the effects of contaminants to liquid chromatography-mass spectrometry (LC-MS) chromatograms. Topics mentioned include the problems caused by contaminants to LC-MS chromatograms, the sources of contaminats including solvents, analytical samples, and LC-MS instrumentation, and the ways to lessen contamination which include wearing of gloves, using of mobile-phase additives, and using of solvent bottles for LC-MS.

A novel "dilute-and-shoot" method is described for the analysis of "bath salts" sold as "legal" highs, including mitragynine and nine synthetic cathinones. The cycle time for this method is 2.5 min. No sample clean-up or extraction was performed. This assay monitors two tandem mass spectrometry (MS/MS) transitions for each of the following 10 analytes: alpha-PVP, butylone, ethylone, MDPV, mephedrone, methcathinone, methedrone, methylone, naphyrone, and mitragynine; and two internal standards: methylone D3 and alpha-PVP D8. This straightforward "dilute-and-shoot" liquid chromatography (LQ-MS/MS method produces acceptable limit of detection (LOD) and limit of quantitation (LOQ) limits without costly extraction and time-consuming concentration protocols. [ABSTRACT FROM AUTHOR]

Specialists in food analysis are increasingly interested in taking advantage of methods that harness the power of ultrahigh-pressure liquid chromatography (UHPLC) and high-resolution mass spectrometry (HRMS). Jon Wong of the Center for Food Safety and Applied Nutrition at the U.S. Food and Drug Administration has been developing such methods for a variety of types of analysis. In this interview, he talks to LCGC about the work to develop these methods and the advantages of their use. [ABSTRACT FROM AUTHOR]

The article discusses the method of ion-pairing chromatography using an ion-pairing reagent as sample additive. It outlines the importance of the reagent's on-column deposition, hydrophobicity and in-sample concentration in achieving the desired retention. Also noted is the achievement of the desired resolution and retention of catecholamines, paraquat–diquat and aminoglycosides on a reversed-phase column and on the mobile phases of liquid chromatography–mass spectrometry.

Systematic toxicological analysis (STA) is an important step in medicolegal investigations of death, poisoning, and drug use. The primary goal is the detection and confirmation of potentially toxic compounds in evidence. This article describes a workflow using nontargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) for reliable compound identification. Tandem mass spectrometry was performed on a low-resolution quadrupole-quadrupole-linear ion trap instrument. Acquired spectra were submitted to automated library search, and positive matches were verified by expert reviewing. After validation, the nontargeted LC-MS/MS technique was integrated in the STA service provided by our laboratory. [ABSTRACT FROM AUTHOR]

There has been an increasing awareness of the presence of polyfluorinated alkyl substances (PFASs) in water. A simple and robust method with quick turn-around time to determine these compounds is essential to providing accurate responses in a timely manner. In the method presented here, direct injection without solid-phase extraction (SPE) allows us to maximize throughput and to minimize background caused by the sample preparation step. We used liquid chromatography with trip le-quadrupole mass spectrometry (LC-MS/MS) to analyze the fluorotelomer and unsaturated fluorotelomer acids included in ASTM International method 7968/7979. Fluorotelomer acids are observed as [M-H]' and [M -H F -H ]\Since the loss of HF in the fluorotelomer acids results in an ion with the same formula as the unsaturated fluorotelomer acids, and these two classes of compounds showed very similar retention times, we reduced the electrospray ionization (ESI) heater temperature to reduce HF loss and minimize false identifications. [ABSTRACT FROM AUTHOR]

The article explores the process of sample preparation and method development for the analysis of polar small molecules with the use of benzoyl chloride (BzCl) derivatization and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Topics include LC-MS/MS metabolomics techniques focused on quantitating a subset of analytes, the key advantage of microdialysis, and the measurement of biogenic amines. The several applications of the techniques to metabolomics analyses are also explored.

Recently, wastewater analysis, also known as wastewater-based epidemiology (WBE), has become an established approach for retrieving additional epidemiological information for evaluating the use of illicit drugs, alcohol, and tobacco at the population level. WBE relies on the analysis of human metabolites (biomarkers) in urban wastewater to monitor and back-estimate substance use in the studied populations. Biomarkers of interest are typically identified and quantified with target analytical methods using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). However, high-resolution and accurate mass spectrometry are also used in WBE to perform suspect and nontarget screening for emerging substances, such as new psychoactive substances and their metabolites, in wastewater and public urinals. This article presents an overview of the recent analytical frameworks and workflows for target and suspect analyses using low- and highresolution mass spectrometry and discusses the latest advances in WBE. Finally, it briefly discusses future perspectives and developments. [ABSTRACT FROM AUTHOR]

The article discusses a method for the determination of very low abundance diagnostic proteins in biological samples of serum using immunocapture analysis which combines the workflow of conventional immunological assays with liquid chromatography-mass spectrometry (LC-MS). The method involves two approaches: the top-down approach and the bottom-up approach. In the top-down approach, proteins are analyzed intact.

The use of antibodies in "bottom-up" liquid chromatography-mass spectrometry (LC-MS) workflows to determine low-abundance biological active proteins in complex human samples has increased in recent years: immunocapture analysis combines the workflow of conventional immunological assays with LC-MS analysis. This article describes typical challenges, such as cross reactivity and the mass spectrometer's dynamic range, as well as the advantages of isoform differentiation and multiplexing. Additionally, some experimental formats of immunocapture bottom-up LC-MS analysis of biological active proteins in complex human samples are discussed. [ABSTRACT FROM AUTHOR]