Slurry sampling for electrothermal atomic absorption spectrometric determination of chromium, nickel, lead and cadmium in sewage sludge

Abstract

The slurry technique was applied for determination of chromium (Cr), nickel (Ni), lead (Pb) and cadmium (Cd) in sewage sludge by electrothermal atomic absorption spectrometry. The graphite furnace temperature programme was optimised. Suspensions prepared in a medium containing 0.5 and 5.0% (v/v) HNO 3 and 0.5 and 5.0 HNO 3 with 0.5% (m/v) glycerol were introduced directly into the furnace. The reliability of the procedure was proved by analysing certified reference material CRM 144R sewage sludge. The contents of Cr, Ni, Pb and Cd in two sludge samples from Poland (Poznań area) ranged between 1.2 and 7.2 mg kg −1 for Cr; 4.5 and 44.9 mg kg −1 for Ni; 0.93 and 103.1 mg kg −1 for Pb and 0.28 and 1.65 mg kg −1 for Cd. The detection limit was calculated as 0.087, 0.054, 0.068 and 0.005 mg kg −1 for Cr, Ni, Pb and Cd, respectively. The relative standard deviation (R.S.D.) measurements for the slurry sampling method was 2.7–4.5% (CRM 144R) and 7.1–9.4% (sewage sludge from Poland).