Abstract: A microwave digestion-flame atomic absorbance spectrometry (FAAS) method was developed to determine trace nickel in foods. The optimal microwave digestion conditions were established as follow: concentrated nitric acid-hydrogen peroxide (4:1, V/V) as digestion solution, digestion time 15 min, and digestion pressure 1.5 MPa. Meanwhile, the optimal solvent medium, activator and instrumental conditions were determined. When present in pH 4.7 acetic acid-sodium acetate buffer, activated by NP-10, the relationship between absorbance and nickel concentration over the range of 3.1 × 10-6– 4.8×10-4 g/L as detected under optimized instrumental conditions obeyed Beer’s law. The detection wavelength was set at 232.6 nm. The limit of detection of this method was 3.1 × 10-6 g/L. The maximum precision RSD for 5 replicate determinations of nickel in cereal grains was 4.2% and average spike recoveries ranged from 95.1% to 106.4%. Compared with the method of GB/T 5009.138-2003, the maximum relative error was not higher than 5.8%.

Key words: nickle, microwave digestion, flame atomic absorbance spectrometry, activator