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Inductively coupled plasma mass spectrometry (ICP-MS) with a time-of-flight (TOF) analyser was used for the determination of chromium, cadmium and lead in six food-packaging materials (paper and paper board). The samples (0.20-0.25 g) were digested in concentrated nitric acid in a high pressure microwave oven at 180 °C within 15 min. Two different plasma conditions were applied: cool plasma conditions (0.76 kW; 0.85, 0.89 and 15.5 l min−1 nebuliser, auxiliary and plasma gas flow rate, respectively) for the determination of chromium and normal plasma conditions (1.21 kW; 0.66, 0.68 and 13.6 l min−1 nebuliser, auxiliary and plasma gas flow rate, respectively) for the determination of cadmium and lead. External calibration was used in combination with rhodium (40 ng g−1) as an internal standard. The detection limits (DL = 3S.D./sensitivity) under the conditions used corresponded to 0.01 ng g−1 (), 0.06 ng g−1 (), 0.07 ng g−1 (), 0.03 ng g−1 () and 0.02 ng g−1 ( and ). The precision (R.S.D.) for six replicate determinations (10 s integration time) of 1 and 10 ng g−1 of each analyte varied from 0.72% () to 4.43% (). The contents of chromium, cadmium and lead in the examined materials were evaluated using the signals of , and . They were in the range: 0.25-0.50 μg g−1 for Cr, not detected (nd) to 0.12 μg g−1 for Cd and 0.28-0.35 μg g−1 for Pb in paper and 0.50-0.64 μg g−1 for Cr, nd to 0.09 μg g−1 for Cd and 0.67-0.99 μg g−1 for Pb in paper board. 相似文献