Inorganic selenium determination

Non-volatile elemental and inorganic selenium, biologically formed in bacterial or plant samples, can be determined via atomic absorption spectrometry (AAS)... 

Wallschlager, D. and R. Roehl. 2001. Determination of inorganic selenium speciation in waters by ion chromatography-inductively coupled plasma-mass spectrometry using eluant elimination with a membrane suppressor. J. Anal. At. Spectrom. 16 922-925. 

Prest, J.E., Baldock, S.J., Fielden, P.R., Goddard, N.J., Brown, B.J.T., Determination of inorganic selenium species by miniaturised isotachophoresis on a planar polymer chip. Anal. Bioanal. Chem. 2003, 376, 78-84. 

Moreno, M.E., Perez-Conde, C., Camara, C. The effect of the presence of volatile organo-selenium compounds on the determination of inorganic selenium by hydride generation. Anal. Bioanal. Chem. 375, 666-672 (2003)... 

In-line filtration without a filtering element is also feasible. To this end, a three-dimensional reactor [299], also called a knitted or knotted reactor (see 6.2.3.4), can be used, as emphasised in the landmark article reporting the flow injection determination of lead in blood and bovine liver by flame atomic absorption spectrometry [300]. The analyte was co-precipitated the complex formed was retained on the inner walls of a knitted reactor and then released by isobutyl methyl ketone and transported to the detector. Interference from iron(III) at high concentrations was circumvented, sensitivity was markedly improved and precise results were obtained. This innovation was recently exploited to remove organic selenium and determine the speciation of inorganic selenium in a flow-injection system with atomic fluorescence spectrometric detection [301]. 

The determination of selenate by difference between total inorganic selenium content and selenite was questioned. Although this method is quite commonly used and acceptable for selenate determination, this does not correspond to a direct measurement of the species hence, this method would not be accepted for certification and it was proposed that the results obtained by difference would be used as confirmative v ues of results obtained by techniques actually separating the Se species e.g. HPLC-ICP-MS or HPLC-HGAAS). 

Nakashima and Toei showed that inorganic selenium in the form of selenous acid reacts with 4-chlorololphenylenediamine hydrochloride to produce 5-chlorobenzene-2,13 selenadiazole which is then extracted into toluene preparatory to determination on a column consisting of SE-30 on Chromosorb W operated at 200 C. Nitrogen is used as a carrier gas and detection was achieved by an electron capture detector. 

A novel interface to connect a ce system with an inductively coupled plasma mass spectrometric (icpms) detector has been developed (88). The interface was built using a direct injection nebulizer (din) system. The ce/din/icpms system was evaluated using samples containing selected alkah, alkaline earths, and heavy-metal ions, as well as selenium (Se(IV) and Se(VI)), and various inorganic and organic arsenic species. The preliminary results show that the system can be used to determine metal species at ppt to ppb level. 

On-line anion exchange LC/ICP-MS methods for selenium and chromium speciation have been published [30], In studies of selenium speciation in environmental samples LC/ICP-MS and LC/ ESI-MS methods have been used for the determination of both inorganic and organic selenium species [43]. For the determination of methyl selenide, strong anion exchange and RP chromatography have been employed [43], while for the determination of seleno-aminoacids, IP RP chromatography with on-line detection based on ICP-MS has been successfully employed [44],... 

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