Rapid determination of lead and cadmium in sewage sludge samples using electrothermal atomic absorption spectrometry with slurry sample introduction

Lead and cadmium concentrations in sewage sludge samples are determined by suspending the ground samples in a solution containing 10% (v/v) concentrat ed hydrofluoric acid, 1% (v/v) concentrated nitric acid, 0.5% (m/v) dihydro gen ammonium phosphate and 0.1% (m/v) sodium hexametaphosphate. Aliquots of 20 mu L of these suspensions (4 mg/mL) are diluted to 1000 mu L with the s ame solution and then injected into the electrothermal atomizer. The drying stage is performed by programming a 400 degrees C temperature, a ramp time of 20 s and a hold time of 15 s on the power supply of the atomizer. No as hing step is used. Platform atomization is carried out at 1600 and 1800 deg rees C for Pb and Cd, respectively. Calibration is performed using aqueous standards in the 5-75 and 0.2-5 mu g/L Pb and Cd ranges, respectively. Resu lts obtained for three certified reference materials and four samples demon strate the reliability of the procedures described.