Determination of Selenium by Platinum-coated Tungsten Coil Trap Hydride Generation-Atomic Absorption Spectrometry

Abstract

A highly sensitive analytical technique was developed in which gaseous hydrogen selenide generated by sodium tetrahydroborate reduction was transported and trapped on a resistively heated platinum-coated W-coil trap for in situ preconcentration. The selenium concentration was determined using hydride generation-atomic absorption spectrometry (HG-AAS). The surface of the W-coil was covered with platinum using the electrodeposition technique in the presence of H-2 and Ar. According to the results of Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDX) images, the ratio of Pt was 54.74% on the W-coil trap surface. Various experimental conditions, such NaBH4 and hydrochloric acid concentration, and carrier gas flow rate, were optimized. In addition, the effect of the hydride-forming elements was quantitatively evaluated. The limit of detection for Se was 21.1 ng/L. The proposed method was also applied to the determination of selenium in certified reference material (SRM 1640a Trace Elements in Natural Water) which showed that the analysis could be performed with a relative error of about 8%. The precision of the method was evaluated and a relative standard deviation (%RSD) lower than 10% was obtained.