Sensitive determination of arsenic and selenium in steels by high power nitrogen microwave induced plasma atomic emission spectrometry coupled with hydride generation technique

:An annular-shaped high power nitrogen microwave induced plasma (Nz-MIP)pro duced at atmospheric pressure by an Okamoto cavity in a surface wave mode h as been used as a new and efficient excitation source for atomic emission s pectrometry (AES). The results show that this kind of MIP source is more st able than conventional low power MIPs and remarkably tolerant to direct and continuous introduction of wet aerosols and molecular gases such as hydrog en, oxygen? air and gaseous hydrides because of its high input microwave po wer. Under the optimized experimental conditions. the best attainable detec tion limits at As(I) 228.812 and Se(I) 196.026 nm by use of N-2-MIP-AES cou pled with hydride generation technique were 2.99 ng As/ml and 0.86 ng Se:ml with a linear dynamic ranges of 5 to 10,000 ng As/ml and I to 5,000 ng Se/ ml. The presence of several diverse elements has been found to cause more o r less a depressing interference with :he determination of arsenic and sele nium by the present technique. Of the several pre-reductants potassium iodi de has been found to be the most preferable to reduce As(V) to As(III) prio r to hydride generation for the determination of total arsenic, i.e., As(II I)+As(V). To the contrary, the heating of sample solutions, previously acid ified in 5 M with hydrochloric acid at 80 degrees C for 20 min was the best way to pre-reduce Se(VI) to Se(IV) before hydride generation for the deter mination of total selenium, i.e., Se(IV)+Se(VI). The proposed method was ap plied to the determination of low concentrations of arsenic and selenium in carbon steels and stainless steels, respectively. The results obtained by this method were in good agreement with the certified values.