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建立了流动注射不等流速在线预富集与火焰原子吸收光谱联用测定大米中痕量镉的新方法。在样品溶液流速不变的情况下,降低络合剂流速,大大提高了吸附预富集效果;此外增加了剩余样品溶液排空步骤,保证了每次试验的准确性和重复性。在进样流速6.0 mL/min,进样时间60 s的条件下,测定15μg/L的镉,流动注射由传统方法的9.0提高到14.7;检出限(3σ)为0.68μg/L;测样频率为37/h;相对标准偏差(RSD,n=11)为2.3%。以体积分数0.1‰的三乙醇胺(TEA)为掩蔽剂,大米中镉的回收率为94.5%~97.8%。
A new method for the determination of trace cadmium in rice by on-line pre-enrichment with flow injection and flame atomic absorption spectrometry was established. In the case of constant flow rate of the sample solution, reducing the flow rate of the complexing agent greatly enhances the adsorption pre-enrichment effect; in addition, the remaining sample solution emptying step is added to ensure the accuracy and repeatability of each test. Under the conditions of 6.0 mL / min injection rate and 60 s injection time, the concentration of cadmium at 15 μg / L was determined by flow injection method from 9.0 to 14.7 with the conventional method. The detection limit (3σ) was 0.68 μg / L. The frequency was 37 / h; the relative standard deviation (RSD, n = 11) was 2.3%. The volume fraction of 0.1 ‰ triethanolamine (TEA) as masking agent, the recovery of cadmium in rice was 94.5% ~ 97.8%.