Sensitive Determination of Antimony in Steels by High Power Nitrogen Microwave Induced Plasma Atomic Emission Spectrometry Coupled with Hydride Generation Technique

Abstract

The feasibility of an annular-shaped high power nitrogen microwave induced plasma (N₂-MIP) atomic emission spectrometry (AES) has been studied for the determination of antimony in combination with hydride evolution method. Under the optimized experimental conditions, the best attainable detection limits at Sb I 231.147 nm line by use of N₂-MIP-AES coupled with hydride generation technique was 1.87 ng Sb/ml with a linear dynamic range of 5 to 10, 000 ng Sb/ml. The presence of several diverse elements was found to cause more or less a depressing interference with the determination of antimony by the present technique. Of the several pre-reductants examined, L-cysteine was found to be the most preferable to reduce Sb⁵⁺ to Sb³⁺ prior to hydride generation. Therefore, L-cysteine was utilized as a pre-reductant for the determination of total antimony, i.e., Sb³⁺+Sb⁵⁺. When antimony in steels was determined, a large amount of Fe³⁺ in the solution caused a severe depressing interference with the antimony determination, while the presence of Fe²⁺ showed little or no significant interference. Of the several interference-releasing agents examined, L-cysteine was found to be the most preferable to reduce Fe³⁺ to Fe²⁺. The proposed method using L-cysteine not only as a pre-reductant but also as an interference-releasing agent was applied to the determination of low concentrations of antimony in carbon steels. The results obtained by this method were in good agreement with the certified values.