Cadmium and lead determination in foods by beam injection flame furnace atomic absorption spectrometry after ultrasound-assisted sample preparation

A simple method for cadmium and lead determination in foods by beam injection flame furnace atomic absorption spectrometry (BIFF-AAS) was proposed. Food slurries were prepared by transferring an exact amount of cryogenic-ground homogenized material (50–100 mg) to centrifuge tubes, followed by addition of 5 ml (up to 2.8 mol l^-1) nitric acid solution and sonication in an ultrasonic bath during 5–10 min. Thereafter, slurries were diluted with water to 10 ml, centrifuged during 5 min at 5400 rpm and 400 (mu)l aliquot of the supernatant was analyzed by BIFF-AAS. The detection limits based on peak height measurements were 0.03 (mu)g g^-1 Cd and 1.6 (mu)g g^-1 Pb for 2% (m/v) slurry (200 mg/10 ml). For method validation, the certified reference materials Pig Kidney (BCR 186) and Rice Flour (NIES 10) were used. Quantitative cadmium and lead recoveries were obtained and no statistical differences were found at 95% level by applying the t-test.