Fecal sterol has been proposed as a chemical indicator of human fecal pollution even when fecal coliform populations have diminished due to water chlorination or toxic effects of industrial effluents. This paper describes an improved derivatization procedure for simultaneous determination of four fecal sterols including coprostanol, epicholestanol, cholesterol and cholestanol using gas chromato...

A highly sensitive and selective high-performance liquid chromatographic (HPLC) method has been developed for the determination of microbial lipopeptides of fluorescent derivatization with 1-bromoacetylpyrene to overcome the limitations of trace detection of lipopeptides in aqueous solutions. The derivatization of lipopeptides with 1-bromoacetylpyrene was conducted at 60°C for 20 min under cata...

The use of perfluorinated anhydrides coupled with perfluoroalcohols for the derivatization of cannabinoids has been well documented. Derivatization is used in the detection of cannabinoids using gas chromatography-mass spectrometry (GC-MS) with both electron impact ionization (EI) and negative chemical ionization (NCI). During method development for the analysis of cannabinoids in biological sa...

A novel and sensitive high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of valproic acid (VPA) in human plasma. The method was based on derivatization of VPA using 2-bromo-2'-acetonaphthone as a new derivatization reagent. Caprylic acid was used as an internal standard (IS). Under the optimized extraction and derivatization conditions, ...

Acetamide has been classified as a possible human carcinogen, but uncertainties exist about its levels in foods. This report presents evidence that thermal decomposition of N-acetylated sugars and amino acids in heated gas chromatograph injectors contributes to artifactual acetamide in milk and beef. An alternative gas chromatography/mass spectrometry protocol based on derivatization of acetami...

Amino compounds, such as amino acids and biogenic amines, are important metabolites that can be found in diverse natural matrices. The most common method for compound analysis nowadays is reversed-phase liquid chromatography tandem mass spectrometry (RPLC-MS/MS). However, due to the polar basic nature of their RPLC retention often insufficient or peaks tailing. Derivatization a way overcome iss...

Fluorescence spectroscopy is the most sensitive optical detection technique used with high-performance liquid chromatography (HPLC). Fluorescence of a molecule can occur naturally or can be achieved by labeling the molecule with a fluorescent tag in a derivatization reaction. A classic application of such a derivatization is for amino acid analysis. The chemical modification can be performed in...

Phospholipids are essential constituents of all living cell membranes. There are many analytical methods available for the quantitative and qualitative determination of phospholipids, but since these molecules lack chromophores, common absorbance based methods are of limited use. Beside mass spectrometry, some less specific approaches that are routinely used are evaporative light scattering det...

Most of the standard methods of solving macromolecular structures involve producing a protein crystal that is derivatized by an anomalous scatterer or heavy atom (MIR, SIRAS, MAD, SAD etc.). The theoretical methodology which underpins the extraction of phase information from such derivatives is widely available in the literature. In addition, there are comprehensive sources of information on th...

larly the oxidation of its side chain, has been investigated by many groups, the conjugates of D metabolites still remain poorly understood. Axelson1 and we2 have reported that 25-hydroxyvitamin D3 [25(OH)D3] 3-sulfate (S) is a major circulating metabolite in humans. Furthermore, we identified the monoglucuronides (G) of D compounds {vitamin D2, vitamin D3 (D3), 25hydroxyvitamin D2, 25(OH)D3, a...