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Nitrogen microwave-induced plasma mass spectrometry was applied to isotope dilution analysis of selenium in biological matrices. The precision of isotope ratio (80Se/ 78Se) measurements of a 100 ng/mL standard solution was 0.5% under practical analysis conditions and could be further lowered by increasing the integration time. Spectroscopic interference at m/z = 80 arising from SOs+ was observed, but the extent was not so much as to cause a serious problem at the sulfur level normally found in biological materials. Isotopic ratios in digested clinical

Nitrogen microwave-induced plasma mass spectrometry was studied for its applicability to the isotope dilution analysis of selenium in biological samples. Spectroscopic interference by calcium, which is present in high concentrations in biological samples, was investigated. No detectable background spectrum was observed for the major selenium isotopes of 78Se and 80Se. No detectable interferences by sodium, potassium, calcium and phosphorus on the isotope ratio 80Se/78Se were observed up to concentration of 200 mg/ml. The method was applied to the analysis of selenium in biological reference materials of marine organisms. The results showed good agreement between the certified and found values.

Insulation level (LIWV 2250 kV) of loo0 kV gas insulated switchgear will be adopted by installing high performance loo0 kV surge amsters. But when temporary overvoltage (TOV) is generated in power systems at line faults and load rejection including Ferranti effects, high performance surge arresters flow discharge current according to the value of TOV. Therefore, it is important to check TOV discharge capability of surge arresters. This paper describes the screening of zinc oxide elements using thermography (thermal uniformity factor) obtained by an infrared radiation camera, with discharge capability of surge arresters for loo0 kV power system.

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