LC–MS

We assessed a simple method based on recovery for the detection of matrix effects and two alternative methods for the rectification of matrix effects in LC–MS: standard addition and the coeluting internal standard method.

Redox reactions are integral parts of many cellular processes. Thus, they are extensively studied in vitro and in vivo. Electrochemistry (EC) represents a pure instrumental approach to characterize direct and indirect effects of redox reactions on bioorganic molecules.

5-Fluorouracil (5-FU) is a low-molecular-weight anticancer drug in clinical use for several solid tumors in humans. Currently, the most widely used methodology for 5-FU quantitation is liquid chromatography–tandem mass spectrometry (LC–MS-MS) with either liquid–liquid extraction (LLE), protein precipitation, or a combination of both as sample cleanup procedures.

This article examines the problem of dermorphin doping in horse racing and presents an effective method for its detection using LC–MS TQ.

Hyphenated approaches to analysis have received much attention over the last three decades to the extent that techniques such as GC?MS, GC?FTIR and LC?MS have ? in the relevant fields ? become indispensable parts of the analyst?s arsenal. This concept has been extended to include multi-hyphenated techniques, where the chromatography is preceded by analyte extraction from a sample matrix. In the field of GC?MS, examples include thermal, sorptive or headspace extraction, with subsequent preconcentration, for instance, by thermal desorption (TD).

This article describes the operating principles of the direct-electron ionization (EI) interface, which is becoming more popular in many LC–MS applications. Matrix effects and the role of direct-EI as a universal detector for small molecule analysis are also discussed in detail. The advantages and drawbacks of this approach are described and a comparison with atmospheric pressure ionization (API) interfaces is made. The potential of direct-EI is illustrated with a selection of practical applications.

Industry veteran Thomas Beesley takes readers on a tour of his experiences in chromatography.

Well-known industry veteran and LCGC EAB member Peter Carr looks back at the early days of the chromatography field and reflects on his own experiences.

The coauthors discuss the various attributes of and approaches to reversed-phase chromatography.

The winners of LCGC's third annual awards were announced at Pittcon 2010.

The authors examine some critical factors with regard to buffers in LC and LC-MS research.

Presented here are four types of evaporation-free extractions that are widely applicable.

Researchers from the University of Barcelona (Barcelona, Spain) analyzed heterocyclic amines in meat samples using pressurized liquid extraction followed by liquid chromatography with tandem mass spectrometry detection (LC?MS-MS).

Researchers at the University of Utah's (Salt Lake City) Sports Medicine Research and Testing Laboratory developed a test for testosterone and epitestosterone in urine that uses liquid chromatography with tandem mass spectrometry detection (LC-MS-MS).

Researchers at the Universit? di Camerino in Camerino, Italy have developed a new GC-MS and LC-MS technique for the determination of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB) in packaged beverages.

Researchers at the Chinese Academy of Sciences and Tsingua University have developed an automated on-line HPLC-MS method allowing injection of a large volume of urine for the improvement of sensitivity using estrogens as analytes.

This month Chromatography Online's Technology Forum looks at the topic of LC-MS and the trends and issues surrounding it. Joining us for this discussion is Scott Berger of Waters Corporation, Graham McGibbon of Advanced Chemistry Development, Inc. (ACD/Labs), Bob Classon of Shimadzu Scientific Instruments, Inc., and Alexander Shaw, Ph.D of Hitachi High Technologies America, Inc.

In the last decade, research on the detection of all groups of doping agents has been investigated by LC-MS, and routine LC-MS screening applications are now available for almost all classes of doping agents.

Vitamin D is a group of fat-soluble prohormones that helps the body absorb calcium and maintain proper levels of calcium and phosphorus in the blood. A vitamin D deficiency results in impaired bone mineralization and leads to bone-softening diseases, such as rickets in children and osteomalacia and osteoporosis in adults, as well as autoimmune and nervous system diseases. A vitamin D overdose can raise blood levels of calcium and cause gastrointestinal symptoms and kidney disease. High blood levels of calcium also can cause heart rhythm abnormalities and calcinosis, the deposition of calcium and phosphate in the body's soft tissues.

This article explores the progress that atmospheric pressure photoionization (APPI) has made in its relatively short history for LC–MS analysis. Specifically, the authors examine the combination of APPI and electrospray ionization (ESI).

This article describes a LC-MS method for the analysis of biodiesels, particularly the characterization of FAMES.

This article aims to demonstrate the unique capability of resin-based mixed-mode solid-phase extraction (SPE) to achieve efficient extraction of basic drugs from plasma. Optimized pore size of the method minimizes retention of high molecular weight matrix components present in the biological fluid samples. The interferences are removed, ensuring extremely clean extracts for subsequent liquid chromatography?mass spectrometry-mass spectrometry (LC-MS-MS) analysis.

Liquid chromatography–mass spectrometry (LC–MS) is a popular technique for the analysis of wine. This article gives an overview of wine analysis and new insights this technique has revealed regarding the composition of wine, possible health benefits, customer safety and the understanding of winemaking processes.

The unique features of silica hydride-based columns are described with a focus on how these columns can expand a laboratory's capabilites in HPLC and LC-MS. Of particular interest is the ability to retain both polar and nonpolar compounds and provide an orthogonal method of analysis for currently existing procedures.

A fast quantitation method for the analysis of N-Methyl Carbamate pesticide residues in vegetables and grains has been developed. High recoveries were obtained for most carbamates screened in all matrices tested at 1 ppb levels. Good linearity of the calibration curves was observed for all analytes, over the range from 1 ppb to 200 ppb levels, with r2 greater than 0.99.

This month's column brings much of the previous discussion on how to interpret mass spectra to a practical examination of detecting substitutions in counterfeit pharmaceuticals.

LC-MS-MS has become a widely used technique for the fast and sensitive quantitation of small molecules. In this article, this approach has been extended to high-throughput quantitative LC-MS-MS analysis under GLP applications for a drug candidate in development from preclinical animal studies through clinical development.

In this month's "MS-The Practical Art," Michael Balogh takes a closer look at insight provided by Chuck McEwen regarding obstacles while using solvents.