A rapid method for the determination of Pb, Cu and Sn in dried tomato sauces with solid sampling electrothermal atomic absorption spectrometry

In this work, lead, copper and tin were determined in tomato sauces by solid sampling graphite furnace atomic absorption spectrometry (SS-GFAAS) and the results were compared with those obtained after sample digestion. The tomato sauce samples were dried at 90 °C for 12 h and directly introduced into the graphite furnace by means of solid auto sampler. Alternatively the dried samples were digested with concentrated HNO₃ (65%) and pipetted into the graphite furnace. After the optimization of the experimental parameters, the average lead, copper and tin concentrations found by the solid sampling and digestion methods in 10 different kinds of tomato sauce samples were not significantly different at 95% confidence level. For solid sampling technique, the limits of detection (LOD) for Cu, Sn and Pb were 10.4, 3.2 and 0.4 ng/g, respectively. Whereas for digestion method, for Cu, Sn and Pb were 6.7, 2.7 and 0.3 ng/g, respectively. The proposed solid sampling technique was fast, simple, the risks of contamination and analyte loss were low.