2003 Volume 89 Issue 5 Pages 587-592
The feasibility of an annular-shaped high power nitrogen microwave induced plasma atomic emission spectrometry (N2-MIP-AES) has been studied for the simultaneous determination of arsenic, bismuth and antimony in combination with the hydride generation method. Under the optimized experimental conditions, the best attainable detection limits at As I 228.812, Bi I 223.061 and Sb I 231.147 nm lines were 7.13, 116 and 14.6 ng/ml for arsenic, bismuth and antimony, respectively, with linear dynamic ranges of 30 to 10000 ng/ml for As or Sb and 300 to 10000 ng/ml for Bi in concentrations. The presence of several diverse elements was found to cause more or less a depressing interference with the proposed technique. Of the several pre-reductants examined, thiourea was found to be the most preferable to reduce arsenic and antimony from their pentavalent state to trivalent one prior to hydride generation. Therefore, thiourea was utilized as a pre-reductant for the determination of total arsenic and antimony concentration, i.e., As(III)+ As(V) and Sb(III)+Sb(V). When arsenic, bismuth and antimony in steels were determined simultaneously, a large amount of Fe(III) in the solution caused a severe depressing interference, while the presence of Fe(II) showed little or no significant interference. Of the several interference-releasing agents examined, L-ascorbic acid was found to be the most preferable to reduce Fe(III) to Fe(II). The proposed method, using both thiourea as a pre-reductant and L-ascorbic acid as an interference-releasing agent, was applied to the simultaneous determination of low concentrations of arsenic, bismuth and antimony in steels. The results obtained by this method were in good agreement with their certified values.