| Atomic fluorescence spectrometry (AFS) has been shown to be a very sensitive and selective technique for the determination of trace metals, with wide linear range, cheap instrumentation, low running cost and simultaneously analytical ability of multielement. It has been widely used in the quantitative analysis of heavy metals in food, environmental protection, medicine, agriculture and so on.This dissertation focused on the development of atomic fluorescence spectrometry in the determination of inorganic arsenic, cadmium and zinc in food.The main results are as followings:1. An ultrasonic-assisted extraction atomic fluorescence spectrometry has been developed for the determination of inorganic arsenic in food. Compared with the national standard method, this method is fast and energy saving with high accuracy and high precision. The recoveries were 95.7% to 100.5% with a RSD of 4.3%(n=6) and detection limit of 0.10 ng/mL. There were no significant difference (P>0.05) between the results of ultrasonic extraction for 30 min and those of the corresponding national standard extracted method for 18 h in the determination of inorganic arsenic in food. Thus, this new method can be used for the determination of trace inorganic arsenic in food samples. It has been showed that the expanded uncertainty was 0.0082 mg/Kg in the rice which inorganic arsenic content was 0.1204 mg/Kg. The evaluation indicated that the fitting of standard curve, the reproducible of measurement and the preparation of standard solution were the main source of uncertainty of inorganic arsenic content in rice.2. A microwave-assisted digestion atomic fluorescence spectrometry has been developed for the determination of trace cadmium in food. The optimal conditions of atomic fluorescence spectrometry for the determination of cadmium were as follows: 8 mm of the atomizer height,260 V of the negative high voltage,50 mA of the lamp current, with 2% potassium borohydride solution (coupled with 2% of sodium hydroxide,1μg/mL of cobalt ion and 20μg/mL of 1,10-ophenanthroline) as a reducing agent,4% of hydrochloric acid solution as carrying current and sample acidity was controlled with 4% of hydrochloric acid solution. Co2+ and 1,10-ophenanthroline have a synergistic sensitization effect on the fluorescence of cadmium. There were no significant difference (P>0.05) between the results of this method and those of the corresponding national standard graphite furnace atomic absorption spectrometry (GFAAS) in the determination of trace cadmium in food, and the measurement of standard samples were in good agreement with the standard values. In addition, the recoveries were 92.8% to 104.6% with a RSD of 4.1%(n=6) and detection limit of 0.010 ng/mL.10 000-fold of Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Li+, Na+, K+,1000-fold of Al3+, Pb2+, Zn2+, Sn2+, Hg2+, Cr6+, Se2+, As3+ and 500-fold of Ag+, Fe2+, Cu2+have no interference in the determination of trace cadmium. Therefore, this method is suitable for the determination of trace cadmium in food with high accuracy, high precision and good selectivity. It has been showed that the expanded uncertainty was only 0.0020 mg/Kg in the rice which the cadmium content was 0.0139 mg/Kg. The evaluation indicated that the fitting of standard curve, the reproducible of measurement, the preparation of standard solution and the recoveries were the the main source of uncertainty of cadmium content in rice.3. An atomic fluorescence spectrometry has been developed for the determination of trace zinc in food based on the microwave-assisted digestion. The optimal conditions of atomic fluorescence spectrometry for the determination of zinc were as follows:8 mm of the atomizer height,260 V of the negative high voltage,50 mA of the lamp current, with 2% potassium borohydride solution (coupled with 2% of sodium hydroxide,1μg/mL of cobalt ion and 3μg/mL of 1,10-ophenanthroline) as reducing agent,4% of hydrochloric acid solution as carrying current and sample acidity was controlled with 4%of hydrochloric acid solution. Co2+ and 1,10-ophenanthroline have a synergistic sensitization effect on the fluorescence of zinc also. There were no significant difference (P>0.05) between the results of this method and those of the corresponding national standard flame atomic absorption spectrometry in the determination of trace zinc in food and the measurement of standard samples were in good agreement with the standard values. In addition, the recoveries were 91.1% to 104.4% with a RSD of 4.7%(n=6) and detection limit of 1.1 ng/mL.1000-fold of Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Li+, Na+, K+,100-fold of Al3+, Pb2+, Cd2+, Sn2+, Hg2+, Cr6+, Se2+ and 500-fold of Ag+, Fe2+, Cu2+, As3+ have no interference in the determination of trace zinc. Therefore, this method is suitable for the determination of trace zinc in food with high accuracy, high precision and good selectivity. It has been showed that the expanded uncertainty was 1.1197 mg/Kg in the rice which the zinc content was 18.0603 mg/Kg. The evaluation indicated that the fitting of standard curve, the reproducible of measurement, the preparation of standard solution and the recoveries were the main source of uncertainty of zinc content in rice.
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