LC–MS

Polyphenols are a well-known group of antioxidants widely diffused as secondary metabolites in plants, vegetables, and fruit. The Column spoke to Nicola Marchetti from the Department of Chemistry and Pharmaceutical Sciences at the University of Ferrara in Ferrara, Italy, about his research into the characterization of polyphenols in red chicory using high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS).

Tips for effective use of chromatography and mass spectrometry for the analysis of antibody–drug conjugates, glycoengineered proteins, and biosimilars.

In metabolomics, LC–MS is a popular technique because of its ability to separate a wide range of metabolites, but the presence of many highly polar analytes in these samples poses a challenge. Benzoyl chloride derivatization can be a practical solution, improving both sensitivity and selectivity.

Wastewater analysis has become an established approach for retrieving additional epidemiological information about the use of illicit drugs, alcohol, and tobacco at the population level. Here, we present an overview of the recent analytical frameworks and workflows for target and suspect analyses using low- and high-resolution mass spectrometry and discuss the latest advances in wastewater-based epidemiology (WBE).

Leading separation scientists share their perspectives on current challenges in separation science and where the field is heading.

Practical examples of how to correct for matrix effects in food testing to obtain reliable quantitative data using LC–MS and GC–MS

We present an empirical assessment of summation integration involving 490 low-pressure GC–MS/MS analyses of 70 pesticides in 10 common fruits and vegetables over the course of 10 days.

Lipidomics, the analysis of lipids by mass spectrometric methods, revolutionized lipid science (1). It provides detailed quantitative information on hundreds of lipid species and opens new possibilities to gain an insight into lipid biology. This helps not only to explain the vital role of lipid species as membrane building blocks, but also to unravel their bioactive functions. Thus, lipid species can act as signaling molecules and modulate membrane properties, which are essential for organelle and membrane protein function. Moreover, the first examples demonstrated their potential as novel biomarkers to monitor human health.

Upon testing with 919 samples, this method produced excellent results.

A cross-disciplinary team of researchers in Tasmania from the fields of separation science, proteomics and metabolomics, immunology and zoology are on a mission to save the Tasmanian devil from extinction using metabolic fingerprinting of serum to identify biomarkers for Devil Facial Tumour Disease (DFTD). The Column spoke to Naama Karu, Rodrigo Hamede Ross, and Richard Wilson to find out more.

Parallel artificial liquid membrane extraction (PALME) is a miniaturized version of liquid–liquid extraction (LLE) and is based on two 96-well plates in a sandwich-like configuration. With a very simple workflow, 96 samples can be processed simultaneously in PALME, providing analyte enrichment, highly efficient sample cleanup, and direct compatibility with liquid chromatography–mass spectrometry (LC–MS). The consumption of hazardous organic solvents is also almost eliminated using PALME as the sample preparation technique. This article summarizes current experiences with PALME, based on work both in a university laboratory and in an analytical services contract laboratory.

Using a liquid chromatography–mass spectrometry (LC–MS) method in conjunction with two complementary types of chromatographic retention modes - reversed phase and aqueous normal phase - various compounds present in mesquite flour extracts were identified. Because of the diverse types of chemical constituents found in such natural product extracts, a single chromatographic mode may not be sufficient for a comprehensive characterization. However, the combination of reversed-phase and aqueous normal phase LC can encompass a wide range of analyte polarity. This characterization of the composition of mesquite flour could be used in future studies to elucidate the beneficial health effects of its consumption.

Part IV of this series takes a closer look at clustering. Clustering can be very useful at observing your data when the sample dimensionality is large. This is a barbarian term meaning that diversity among your samples may be wide. In that case, the space reduction provided by principal component analysis (PCA) is not always convincing, because the simplification provided by a single two-dimensional plot erases too much information. Clustering allows you to preserve more information.

Tips and tricks to help you recognize and solve the most common SPE problems.

How to optimize the key variables in LC–MS analysis

Here we propose an exemplary workflow for the analysis of phenolic extracts (i.e. wine) enabling confident differential analysis using high performance liquid chromatography in combination with low-field drift tube ion mobility quadrupole time-of-flight mass spectrometry (HPLC×IMS-QTOFMS). In this workflow, single-field collisional cross section values from low-field drift-tube IMS using nitrogen as drift gas (DTCCSN2) are readily extracted in addition to a retention time and a high resolution mass spectrum for each compound. “Alternating frames” experiments utilizing post-drift tube fragmentation also allow drift time-aligned MS/MS spectra to be obtained. Molecular feature extraction was highly repeatable with average precision values of 0.28% for retention time, 0.18% for drift time, and 1.5 ppm m/z determined for 233 molecular features found in all six technical replicates. The improved selectivity of this strategy increases confidence in intersample molecular feature alignment (i.e. compound identity confirmation), including the resolution of co-eluting isomeric compounds.

The power of nontargeted metabolite profiling is illustrated in a study focused on the determination of molecular markers in malting barley that are predictive of desirable malting quality for brewing applications. The metabolite extraction, detection, and analysis methods are high throughput and reproducible, and therefore, this approach represents a practical addition to the plant breeder’s molecular toolbox.

This study of a selected group of PPCP contaminants in eastern North Carolina demonstrates the advantages and disadvantages of LC–MS and GC–MS as well as SPE and liquid–liquid extraction.

An LC–MS method for simultaneous quantification of buprenorphine and three metabolites: norbuprenorphine, buprenorphine glucuronide, and norbuprenorphine glucuronide.

Validation of this rapid bioanalytical method for the determination of moxidectin in cattle hair demonstrated that the method is accurate, reliable, and reproducible.

High-resolution mass spectrometry (MS) is not readily compatible with chromatographic techniques using high-salt mobile phases. This study presents the development and use of 2D-LC–MS via an on-line desalting step for the analysis of monoclonal antibodies and antibody–drug conjugates.

Measuring trypsin inhibitors in legumes is important to feed processors, who are concerned with providing high-quality products for animal feed. In this study, a rapid, accurate, and precise method for the quantification of trypsin inhibitor activity is evaluated.

The development of various analytical MS methods to investigate the chemical composition of liquids used in electronic cigarettes and characterize their quality is presented in this study.

A review of the central role LC–MS plays in characterizing mAbs and biosimilars, including highlights of top-down and middle-up approaches to measure the intact masses of mAbs and their subunits, the current state of peptide mapping techniques, and glycoprofiling methods.

The last decade has seen a series of advances in the field of liquid chromatography that have resulted in improvements for many clinical diagnostic services. These innovations have included the expansion of superficially porous particle columns, new or improved stationary phase options, and “user-friendly” multiple-channel HPLC instrument options that allow sequential analysis-a boon for low and moderate throughput laboratories with limited hardware. As a result, diagnostic services are able to offer faster turn-around-times and measure analytes in patient types and disease states that were previously problematic. This article presents examples of the impact these innovations have had in a number of hospital settings.