LASER-INDUCED FLUORESCENCE DETERMINATION OF THALLIUM IN SEDIMENTS

A simple dissolution procedure is decribed for sediments to be analyze d for thallium by Laser-Excited Atomic Fluorescence Spectrometry (LEAF S), It simply uses a nitric - hydrofluoric acid mixture at room temper ature (a ''cold dissolution'' procedure as opposed to the hot acid dig estion) followed by a dilution with water (as opposed to the tedious s teps of separation and preconcentration). Excellent accuracy (91-106% recoveries) and precision (4-10% relative standard deviation) were dem onstrated by the use of five sediment reference materials of diverse o rigins. The detection limit was estimated to be 0.5 ng/g of thallium. Additionally, a hot plate digestion procedure, using an in-house desig ned semi-enclosed Teflon beaker, was also investigated; its analytical results agreed with certified values and confirmed the adequacy of th e cold dissolution technique. The method is being applied to study the sediment - water interactions in lake environments.