Determination of Trace Residues of 8 Elements in Rice Grain Crop by Inductively Coupled Plasma Mass Spectrometry with Automatic Graphite Digestion

The crushed rice sample (about 0.3 g) was taken and digested by automatic graphite digestion according to the setting digestion procedure. After digestion, its volume was made up to 25 mL with 5% (φ) nitric acid solution, and chromium, cadmium, arsenic, aluminum, strontium, lead, barium and thallium were determined in the above solution by inductively coupled plasma mass spectrometry. Internal standard method was used for quantitative analysis. As shown by the results, the linear ranges of standard curves of chromium, cadmium, arsenic, aluminum, strontium, lead, barium and thallium were all 0.01-8.0 μg·L^-1, with detection limits (3S/N) of 0.006, 0.011, 0.009, 0.017, 0.009, 0.008, 0.012, 0.018 μg·kg^-1, respectively. Recovery test was carried out by the standard addition method, giving results in the range of 83.9%-105%, with RSDs (n=6) of the determined values less than 5.0%. This method was applied to the determination of actual rice samples. The detection rates of aluminum and barium were 100%, with detection amounts of 0.49-1.02 mg·kg^-1 and 0.019-0.071 mg·kg^-1, respectively. The detection rates of cadmium and lead were 33%, with detection amounts of 0.028-0.042 mg·kg^-1 and 0.025-0.074 mg·kg^-1 respectively. Chromium, arsenic, strontium and thallium were not detected.