Analysis of Aqueous Solutions by Laser-Induced Breakdown Spectroscopy of Ion Exchange Membranes

Abstract

Elemental analysis of solutions can be achieved by concentrating and immobilizing the metal ions into a commercially available ion exchange polymer membrane followed by laser-induced breakdown spectroscopy. Two methods of sample preparation were investigated: filtering the solution through the ion exchange membrane with suction, and placing the membrane in the solution and allowing the ions to equilibrate with the membrane. The membrane was then ablated with the focused energy of a Nd:YAG laser at 1064 nm. The emitted light was collected by an echelle spectrometer through a fiber-optic cable and detected with an intensified charge-coupled device (CCD). Ten different metals, most covered by the Resource Conservation and Recovery Act (RCRA), were studied. The concentrations of barium, cadmium, chromium, cobalt, copper, silver, lead, mercury, nickel, and zinc can be measured simultaneously with limits of detection ranging from 2 μg/mL to 4 ng/mL. The linear range is 2–6 orders of magnitude depending upon the element and sampling method. The major advantages of the technique are the multielement capability and the ease of sample preparation.