Evaluation of LIBS under controlled atmosphere to quantify cadmium at low concentration in landfill leachates

Abstract

Laser-induced breakdown spectroscopy (LIBS) is a fast, relatively simple and precise alternative technique to measure heavy metal concentrations in solid, liquid and gaseous materials with limits of detection compatible with the recommended values for soil and water quality criteria. In this paper, a conventional LIBS apparatus has been used for the quantitative analysis of cadmium (Cd) in a landfill leachate under controlled atmospheric and reduced pressure (100 Torr) conditions. LIBS analysis was performed using a background correction and the sum of the areas above the three Cd transitions peaks (Cd II at 214.44 nm; Cd II at 226.50 nm and Cd I at 228.80 nm). Under reduced pressure the linear correlation of the calibration curve increased from 0.96 to 0.99, with respect to the atmospheric pressure. The limit of detection for Cd improved by a factor of 5, from 5 to 1 mg kg−1, and the concentrations measured by LIBS were assessed by complementary induced coupled plasma-optical emission spectroscopy (ICP-OES). These results indicated that LIBS under controlled atmosphere can be recommended for the analytical quantification of Cd in landfill leachates.