Pathem, Bala Krishna, Capillary electrophoretic determination of selenocyanate and selenium and tellurium oxyanions in bacterial cultures. Master of Science (Chemistry), August, 2007, Sam Houston State University, Huntsville, Texas. 64 pp. (pdf version of this thesis)
The purpose of this work was, in part, to develop a capillary electrophoretic method for the simultaneous estimation of selenium and tellurium anions in the presence of complex bacterial growth media. A simple capillary zone electrophoretic method for the determination of biospherically important oxyanions of selenium and tellurium and a biologically produced Se-containing anion, SeCN-, was developed. The method uses direct UV absorption detection. Time course experiments with time slices as short as 6 min are possible. This method's detection limits and linear range compare well to other previously published methods involving complex biological matrices. The metalloidcontaining anions examined were selenocyanate, selenite, selenate, tellurite and tellurate. This method was applied to live bacterial cultures of two different bacteria in two different growth media in time course experiments following the changes in metalloid-containing anion concentrations. The results show that this method is a useful means of following the biological processing of these analytes in bacterial cultures.
Experiments were also designed to detect the biological production of selenocyanate in Se-amended bacterial cultures using IC-ICP-MS. A selenium-resistant bacterium, 130404, when amended with 1.0 mM selenate biologically produced selenocyanate in replicate cultures grown to stationary phase. The amounts produced were statistically significantly different than the amounts of SeCN- produced in sterile but warmed growth media. The headspace gases above growing cultures with or without metalloid amendments were analyzed using gas chromatography. Organo-selenium compounds that were detected were methaneselenol, dimethyl selenide, dimethyl selenenyl sulfide, dimethyl diselenenyl sulfide, dimethyl diselenide. Two late eluting peaks were observed in the same cultures that were not characterized but can reasonably be inferred to be dimethyl diselenenyl sulfide and dimethyl triselenide.
Keywords: selenocyanate, capillary zone electrophoresis, tellurite, selenate, selenite