LC–MS

Enzyme immunoassay (EIA) is a conventional drug screening technique, but it can be limited by cross-reactivity that can lead to high false positive rates.

We recently spoke to Gary Duncan and Wendy Russell of the Rowett Institute of Nutrition & Health in Aberdeen, Scotland, about the significance of phytochemical bioavailability to human health and the important role of liquid chromatography linked to tandem mass spectrometry (LC–MS-MS) in their research.

Click here to view the complete E-Separation Solutions newsletter from February 20, 2014.

Secondary parameters in the interface and mass analyzer can have a major impact on sensitivity and reproducibility. Here, we examine how and when to consider optimizing these parameters through a study of the working principles of LC–MS analysis.

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.