Determination of As, Hg, S, and Se in liquid jets by laser-based optical diagnostic technique

Abstract

Laser-induced breakdown spectroscopy (LIBS) has been evaluated for measurement of As, Hg, S, and Se in aqueous samples. Single pulse (SP) and double pulse (DP) LIBS, with a 1064 nm Nd: YAG laser source, were utilized to generate micro plasma from the surface of a liquid jet containing these elements. Plasma emission was collected at a 45° angle with the laser beam for As and Se detection in UV wavelength range. However, the confocal mode was used to collect the atomic emission for Hg and S detection in visible and near IR range, respectively. Atomic emission lines 228.81 nm for As, 546.07 nm for Hg, 921.2 nm for S, and 196.09, 203.98 and 206.32 nm for Se were detected in the LIBS spectra. Calibration curves were developed to estimate the limit of detection for each analyte and found to be 2, 16, 16, and 29 ppm for As, Hg, S, and Se, respectively, with SP LIBS and 0.4, 8, 8 and 11 ppm, respectively, with DP LIBS. The study has implications in monitoring of these pollutants in flue gas desulfurization (FGD) wastewater.