RAPID-DETERMINATION OF LEAD, CADMIUM AND THALLIUM IN CEMENTS USING ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY WITH SLURRY SAMPLE INTRODUCTION

A method is proposed for the determination of Pb, Cd and Tl in cements by ETAAS. The samples are suspended in a medium containing 10% v/v et hanol and 1% v/v both conc. nitric and hydrofluoric acids and are dire ctly introduced into the electrothermal atomizer. The drying stage is performed by programming a 400 degrees C temperature, a ramp time of 5 s and a hold time of 30 s on the power supply to the atomizer. No ashi ng step is used. Atomization is carried out at 2100, 1800 and 1700 deg rees C for Pb, Cd and Tl, respectively. For Cd determination, ammonium dihydrogen phosphate is added to the suspension medium. No modifier o ther than hydrofluoric acid is required for the Pb and Tl determinatio n. It is shown that the results obtained by using direct calibration w ith aqueous standards for five commercial samples agree with those fou nd by means of the standard additions method.