No abstract

The occurrence and form of selenium and mercury were investigated in Indian Mustard, Brassica juncea, a selenium accumulating plant, which had been co-exposed to varying concentration levels of these two elements. Plants were grown and exposed in hydroponic solutions. Following exposure, root exudates were collected in fresh solutions and the head-space around the aerial portions of the plants was sampled. These samples and the harvested plant tissues were then processed for determination of Se and Hg-containing compounds. For the plant tissues, roots, stems and leaves were separated and extracted using a sequential procedure that removed watersoluble species, water-soluble proteins, and dodecyl sulfate-soluble proteins. Size exclusion chromatography allowed further fractionation. High molecular-weight selenium/mercurycontaining compounds were found primarily in the plant root extract. Evidence suggests that a Se and Hg complex of high molecular weight may be protein associated. For the analysis of exudate solutions, ion-pairing reversed phase chromatography coupled to ICP-MS was used. Multiple selenium and mercury species were detected, with one mercury-containing compound observed eluting near selenocystine. Plant head-space was sampled with solid phase microextraction and analyzed with GC-ICP-MS and GC-TOFMS. Apart from the primary selenium volatiles and elemental mercury, no volatile species simultaneously containing Se and Hg could be detected.

No abstract

Speciation of iodine in commercially available commonly consumed seaweed samples was performed using a multidimensional chromatographic approach coupled with inductively coupled plasma mass spectrometry (ICP-MS) for element specific detection. Analysis of alkaline extract (0.1 mol l À1 NaOH) by size-exclusion chromatography coupled to ICP-MS (0.03 mol l À1 Tris-HCl, pH 8.0) indicated the association of iodine with both high as well as low molecular weight fractions in Wakame, while in case of Kombu, only low molecular weight iodine species were found. Likely association of iodine with protein as well as polyphenolic species was indicated in the case of Wakame. Anion-exchange chromatography coupled to ICP-MS (0.005 mol l À1 NaOH) confirmed that the most predominant inorganic iodine species present in both type of seaweeds is iodide. Protein bound iodinated species were hydrolyzed by enzymatic digestion using Proteinase K. Analysis of the hydrolysate using reversed-phase HPLC-ICP-MS (0.01 mol l À1 Tris-HCl pH 7.3 : 0.01 mol l À1 Tris-HCl pH 7.3 and 50% MeOH) revealed the presence of monoiodotyrosine and di-iodotyrosine in Wakame, which was later identified by matching the chromatographic retention time with the retention time of commercially available standards.w WEB: http://www2.uc.edu/plasmachem/default.html.

Inductively coupled plasma-MS (ICP-MS) and its combined use with molecular mass spectrometric techniques have become the most promising detection techniques in speciation studies. High sensitivity and element specificity of ICP-MS has the advantage of detecting trace amounts of the species of interest in complex matrices. This review is divided into two parts. In the first part, suitable use of ICP-MS either online or offline with currently used separation techniques such as HPLC, CE, and gel electrophoresis in speciation analysis is briefly discussed. In the second part, recent applications (1999-2005) of phosphorus speciation is presented to elucidate the importance of ICP-MS in separation methods and to illustrate its importance in nonmetal detection.