Quantitative selenium speciation in human urine by using liquid chromatography-electrospray tandem mass spectrometry.

A liquid chromatography-electrospray-tandem mass spectrometry (ES-MS/MS) method was developed for the speciation analysis of four organic selenium species of relevance to human urinary metabolism, namely trimethylselenomium ion (TMSe(+)), selenomethionine (SeMet) and the two selenosugars, methyl 2-acetamido-2-deoxy-1-seleno-β-D-galactos/-glucos-amine (SeGalNAc and SeGluNAc, respectively). Their chromatographic separation was achieved by using a cation exchange pre-column coupled in-series with a reversed-phase high-performance liquid chromatography column, along with an isocratic mobile phase. Online detection was performed using ES-MS/MS in selective reaction monitoring mode.

Individual variability in the human metabolism of an arsenic-containing carbohydrate, 2',3'-dihydroxypropyl 5-deoxy-5-dimethylarsinoyl-beta-D-riboside, a naturally occurring arsenical in seafood.

We report studies on the variability in human metabolism of an oxo-arsenosugar involving the ingestion of a chemically synthesized arsenosugar and quantitative determination of the arsenic metabolites in urine and serum by HPLC coupled with arsenic-selective mass spectrometric detection (ICPMS, inductively coupled plasma mass spectrometry). The total, four-day, urinary excretion of arsenic for six volunteers ranged widely from ca. 4-95%.

Cytotoxic, genotoxic and cell-cycle disruptive effects of thio-dimethylarsinate in cultured human cells and the role of glutathione.

Thio-dimethylarsinate (thio-DMA), a recently discovered urine metabolite in humans, was investigated for its cytotoxic, genotoxic and cell-cycle disruptive effects in the cultured human hepatocarcinoma cell line, HepG2, and Syrian hamster embryo cells. In addition, the role of glutathione (GSH) on the cytotoxic effects of thio-DMA was investigated in terms of the effects of GSH depletion and the effects of exogenously added GSH. LC50 values of arsenicals for cells incubated for 48 h were 0.

Thio-dimethylarsinate is a common metabolite in urine samples from arsenic-exposed women in Bangladesh.

Over the last 6 years, much work on arsenic species in urine samples has been directed toward the determination of the reduced dimethylated arsenic species, DMA(III), because of its high toxicity and perceived key role in the metabolism of inorganic arsenic. Recent work, however, has suggested that DMA(III) may at times have been misidentified because its chromatographic properties can be similar to those of thio-dimethylarsinate (thio-DMA). We analyzed by HPLC-ICPMS (inductively coupled plasma mass spectrometry) urine samples from 75 arsenic-exposed women from Bangladesh with total arsenic concentrations ranging from 8 to 1034 microg As/L and found that thio-DMA was present in 44% of the samples at concentrations ranging mostly from trace amounts to 24 microg As/L (one sample contained 123 microg As/L).

Nonlinear optical properties of diazabutadienes and -hexatrienes; experimental and computational aspects.

Donor-acceptor substituted diazabutadienes and -hexatrienes were prepared by straightforward procedures and their linear optical (UV-vis) and nonlinear optical second harmonic generation (SGH) properties investigated in a combined theoretical and experimental study. Theoretical and experimental results were in reasonable agreement. For the compounds in this study, which contained a p-nitrophenyl group as electron acceptor, the p-dimethylaminophenyl group was the most powerful electron-donating group, leading to the highest maximum absorption wavelengths, as well as to the maximum SHG efficiency.