Selenium-specific detector

Kolasa et al. [562] have reported changes in the degree of oxidation of chromium (from Cr6+ to Cr3+) in the course of probe mineralisation of PE for AAS analysis. HPLC-ICP-MS has been used as a selenium-specific detector [563]. Other selenium speciation work by ICP-MS has been reported [564]. Numerous other examples of speciation analysis have been described for the most appropriate techniques (Chapter 7). 

D. Chakraborli, D.C.J. Hillman, K.J. Irgolic, and R.A. Zingaro, Hitachi Zeeman graphite furnace atomic absorption spectrometer as a selenium-specific detector for ion chromatography. Separation and determination of selenite and selenate, j. Chromatogr., 249,81,1982. 

For practical speciation, an analytical method must be specific to a particular selenium species or that species must be separated in time or space before arriving at a selenium-specific detector. Radioim-munological assays for selenoproteins offer very low detection limits but require the proteins to be isolated in amounts sufficient for antibody production. Selenium has been speciated into selenate, selenite, elemental Se, and organoselenium using fractionation techniques and X-ray absorption spectroscopy, but little has been done in speciating organic forms. 

Fangshi, L., Goessler,W., and Iigohc, K. J. (1999). Determination of seletrium compounds by HPLC with ICP-MS or FAAS as selenium-specific detector. Chin.J. Chromatogr. 17(3), 240. 

Fig. 2.2. Ion chromatograms of a synthetic river water (277 mg chloride, 69 mg sulfate, 5 mg 1 phosphate) spiked with 400 micrograms selenium as selenite and 400 micrograms selenium as selenate recorded with a conductivity detector and a Hitachi Zeeman graphite furnace atomic absorption spectrometer (GFAAS) as the selenium-specific detector (Dionex Model 16 ion chromatograph, 1.0 ml sample, 50 x 3 mm anion precolumn Dionex 30008 mobile phase 0.008 M aqueous Na2C03, 0.46 ml min 150 X 3 mm anion separator column Dionex 30589 250 x 3 mm anion suppressor column Dionex 30066. GFAAS drying 120°, 60 sec no ashing atomization 2500°, 6 sec Se lamp 10 niA, 196.0 nm 80 sec between injections retention time in min). Redrawn from the Journal of Chromatography [9] by permission of Elsevier Science Publishers and the authors.

The determination of organic selenium compounds is done preferably by GC coupled to element-or molecule-specific detectors, such as GC-AED or molecular mass spectrometric detection (GC-MS).240 In this case, ICP-MS detection does not yield the improvement in sensitivity otherwise seen, which is due to spectral interferences. Dietz et al.241 have compared the analytical figures of merit of three detector systems for GC (AED, atomic fluorescence spectroscopy (AFS), and ICP-MS), arriving at the conclusion that GC-AED is the most sensitive and most practical... 

T. Guerin, A. Astruc, M. Astruc, Speciation of arsenic and selenium compounds by HOLC hyphenated to specific detectors a review of the main separation techniques,... 

The conductivity detector was set at a sensitivity that would have produced an acceptable signal for the selenium compounds in the absence of the other ions. Because of the high sensitivity setting on the detector and the high concentrations of chloride, sulfate, and phosphate relative to selenite and selenate, the recorder pen is off the chart for retention times between 8 and 25 minutes, and signals for selenite and selenate cannot be reliably located. However, when a graphite furnace atomic absorption spectrometer was employed as the selenium-specific... 

Bortnikov et al separated bistriethylsilyl sulphide and related compounds containing silicon, selenium, sulphur, germanium, tellurium and/or tin as the central linking atom at 254°C in a stainless steel column (100cm x 0.4cm) packed with Chromosorb W, supporting 20% of Apiezon L, with helium as carrier gas and a thermal conductivity detector. Specific retention volume data are reported. 

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