UNLABELLED BACKGROUND Methylcarbamate (MC) and ethylcarbamate (EC) are toxic compounds that commonly exist in fermented food and beverages. In order to estimate the risk for their exposure, a sensitive simultaneous analytical method is required RESULTS A simultaneous determination of MC and EC was described based on derivatization with 9-xanthydrol and consecutive detection using gas chrom...

Liquid chromatography/mass spectrometry (LC/MS) is now considered to be the most promising analytical method for the determination of biological substances, especially nonvolatile or highly polar substances. However, some compounds do not show enough sensitivity in LC/MS and soft-ionization methods commonly used in LC/MS, such as electrospray ionization (ESI) and atmospheric pressure chemical i...

4-Hydroxybenzoate is a phenolic derivative of alkyl benzoates and is a widely used preservative in cosmetic and pharmaceutical products. The presence of 4-hydroxybenzoates in the human body may result from the use of pharmaceutical and personal care products. These compounds are also known to exhibit estrogenic and genotoxic activities. The potential adverse effects of these compounds include e...

We report here the solid phase synthesis of RNA and DNA oligonucleotides containing the 2'-selenium functionality for X-ray crystallography using multiwavelength anomalous dispersion. We have synthesized the novel 2'-methylseleno cytidine phosphoramidite and improved the accessibility of the 2'-methylseleno uridine phosphoramidite for the synthesis of many selenium-derivatized DNAs and RNAs in ...

The state of the art of analytical procedures based on solid-phase microextraction (SPME) and its applications to tin, mercury, arsenic, antimony, chromium, selenium, and lead determination in abiotic and biotic matrixes are critically reviewed from 1994 to present. First, sample pretreatment prior to SPME is evaluated, including a description of the most usual leaching procedures for sediment,...

A procedure for the precise determination of the D and L isomers in a given sample of an amino acid has been based upon chromatographic separation of the diastereoisomeric dipeptides obtained by derivatization with an L-amino acid N-carboxyanhydride. The conditions for the preparation of dipeptides developed by Hirschmann and associates make the derivatization step simple and rapid; the couplin...

This paper reviews studies on dissolution, derivatization, and nanomaterial processing of chitin using an ionic liquid as useful media. Because chitin is the second most abundant polysaccharide on the earth after cellulose, there is major interest in conversion of native chitin resources into various useful materials after proper dissolution in suitable solvents. For the derivatization and nano...

1 Amino Acid Analysis: An Overview Margaret I. Tyler ..................................................................................... 1 2 Amino Acid Analysis, Using Postcolumn Ninhydrin Detection, in a Biotechnology Laboratory Frank D. Macchi, Felicity J. Shen, Rodney G. Keck, and Reed J. Harris ............................................................................. 9 3 Purification ...

Coupled with off-line extraction, a pre-column derivatization liquid chromatographic fluorescence detection (LC-FL) procedure was developed for the determination of atrazine and simazine in soil, crop and water samples. Concentrations in real samples were expected to be at or below the low ng/g level, which requires pre-concentration of analytes and improved detection. 4-(2-Phthalimidyl) benzoy...

Selenium-derivatization of RNA is a powerful and advantageous alternative to conventional heavy atom derivatization techniques that are required for the phasing of X-ray crystallographic diffraction data. Among several possibilities, the 20-methylseleno (20-SeCH3) modification has been most widely explored and was responsible for a series of important RNA structure determinations, such as the D...