Hydride Generation and Laser Spectroscopy Techniques for Trace Analytical Measurements of Antimony and Selenium

Abstract

Hydride generation (HG) sample introduction increases the sensitivity for certain metal species by converting them to their gaseous forms for measurement by atomic spectrometry techniques. In this work, measurement methods have been developed for the trace analysis of antimony (Sb) and selenium (Se) using HG coupled to Laser Induced Fluorescence (LIF) or Laser Induced Breakdown Spectroscopy (LIBS) detection techniques. In the LIF studies, aqueous samples of Sb are subjected to HG and the Sb hydride is carried to the flame which acts as an atomization source. The wavelengths of absorption and fluorescence emission for Sb were found to be 212.7 nm and 259.8 nm, respectively. The intensity of fluorescence was plotted against the concentration of Sb used. It was found that the intensity was linearly related to the concentration of Sb in the range 0.3-10 ppb. The limit of detection (LOD) was found to be 0.003 ppb. A similar technique has been used for the determination of Sb and Se in aqueous samples using LIBS. In this approach, a plasma instead of a flame is used to excite Sb and Se atoms and the atomic emission is measured at wavelengths of 259.9 nm and 196.1 nm, respectively. Using these wavelengths, calibration curves were plotted for intensity of emission against different concentrations of Sb and Se. From the calibration curve, the slope and LOD have been determined. The results of the studies have been evaluated to show the relative performance of each technique.