An analytical method for the determination of stanozolol and its metabolites, based on liquid chromatography mass spectrometry was validated and used during the preparation of lyophilised samples of bovine urine. A serie of lyophilised samples was prepared and characterised in terms of mass concentration of 16ß-hydroxy-stanozolol and homogeneity.

The reversible phosphorylation of proteins is a dynamic process that plays a major role in many vital physiological processes by transmitting signals within cellular pathways and networks. Proteomic measurements using mass spectrometry are capable of characterizing the sites of protein phosphorylation and to quantify their change in abundance. However, the low stoichiometry of protein phosphory...

Recent advances in mass spectrometry are enabling improved analysis of endogenous metabolites. Here we discuss several issues relevant to developing liquid chromatography-electrospray ionization-mass spectrometry methods for targeted metabolomics (i.e., quantitative analysis of dozens to hundreds of specific metabolites). Sample preparation and liquid chromatography approaches are discussed, wi...

A viable, quick, and reliable method for determining urinary creatinine by liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed and used to evaluate spot urine samples collected for the Washington Environmental Biomonitoring Survey (WEBS): part of the Washington State Department of Health, Public Health Laboratories (PHL). 50 µL of urine was mixed with a 1 : 1 acetonitrile/wa...

Levels of nonsulfated and sulfated tibolone metabolites were determined in plasma, urine, and feces from six ovariectomized, mature female cynomolgus monkeys after a single dose and multiple p.o. doses (including bile) of tibolone using validated gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry assays. In plasma, the predominant nonsulfated metabolite afte...

A new analytical method employing liquid chromatography/tandem mass spectrometry (LC/MS/MS) with a column-switching system was developed for quantitative determination of leukotriene E4 (LTE4) in human urine. A column-switching system using a trapping column, which concentrates the analyte and removes salts and other water-soluble contaminants, allowed direct injection of human urine. Because s...

The complexity and diversity of biological samples in proteomics require intensive fractionation ahead of mass spectrometry identification. This work developed a chromatographic method called virtual three-dimensional chromatography to fractionate complex protein mixtures. By alternate elution with different pHs and salt concentrations, we implemented pH and salt steps by turns on a single stro...

A method for the determination of 42 hazard residues required by 'Japan Positive List System' in bottled water was described. Hazard compounds in bottled water were extracted with a solid phase extraction step using C18 disks. Determination was carried out by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography-tandem mass spectrometry (LC/MS/MS). The disk extraction has high ...

Glycation of immunoglobulin G (IgG) can result from incubation with a reducing sugar in vitro or during circulation in vivo. Upon injection of a recombinantly produced human therapeutic IgG into humans, changes in the glycation levels could be observed as a function of circulation time. Mass changes on the individual IgG polypeptide chains as the results of glycation were determined using rever...