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目的建立石墨炉原子吸收光谱法批量测定食品中镉未知高低含量相差大的分析方法。方法食品样经硝酸-双氧水消解后,应用动态三磁场塞曼校正技术模式,通过线性扩展,使用平台石墨管,在228.8 nm波长下进行镉的测定。结果仪器设定动态3-磁场模式,同时也能得到2-磁场模式的数据和校正曲线,2-磁场模式标准曲线段(0~3μg/L):Abs=0.0749×Cone+0.0102,R2=0.991,特征浓度为0.11μg/L/1%A;3-磁场模式标准曲线段(3~10μg/L),Abs=0.0225×Cone+0.0202,R2=0.9997,特征浓度为0.077μg/L/1%A;最低检测浓度0.08μg/L;对国家标准大米GBW10043、GBW10045分析,RSD为0.25%~1.63%,对本地采集的样本回收率95.5%~110%。结论方法保持了两种模式的优点,检出限低、快速、准确、线性范围宽,能满足批量食品样品中镉的不同浓度同时分析。
OBJECTIVE To establish a method for the determination of cadmium content in food by graphite furnace atomic absorption spectrometry. Methods After the samples were digested by nitric acid and hydrogen peroxide, the dynamic three-magnetic Zeeman calibration technique was used to measure the cadmium at 228.8 nm by linear expansion and by using a platform graphite tube. Results The instrument set the dynamic 3-magnetic field mode and obtained the data and calibration curve of 2-magnetic field mode. The standard curves of 2-magnetic field mode (0-3μg / L) were Abs = 0.0749 × Cone + 0.0102 and R2 = 0.991 , The characteristic concentration was 0.11μg / L / 1% A; the standard curve of 3-magnetic field mode was 3 ~ 10μg / L, Abs was 0.0225 × Cone + 0.0202, R2 was 0.9997, A; the lowest detection concentration of 0.08μg / L; for the national standard rice GBW10043, GBW10045 analysis, RSD 0.25% ~ 1.63%, the local collection of samples recovery 95.5% ~ 110%. Conclusions The method maintains the advantages of the two modes. The detection limit is low, fast, accurate and linear. It can meet the simultaneous analysis of different concentrations of cadmium in bulk food samples.