快速分离富集火焰原子吸收测定大米中的痕量镉

FI on-Line Adsorption and Preconcentration Coupled with FAAS for the Determination of Trace Cadmium in Rice

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 flow injection（FI） unequal flow rate complexing preconcentration system coupled to flame atomic absorption spectrometry（FAAS） was developed for the determination of trace cadmium in rice.During the preconcentration procedure,complexant and metal solutions were under different peristaltic pumps.Through decreasing the flow rate of the complexant,the flow rate of the metal-complex compound was decreased in the KR.The low flow rate benifiting the adsorption of the metal-complex compound on to the inner walls of the KR.With 60 s（sample throughput of 37/h） of sampling at a flow rate of 6.0 mL/min,an enrichment factor（EF） of 14.7（higher than 9.0 achieved by conventional elution method） and a detection limit（3） of 0.68 μg/L were obtained.The precision（RSD,n=11） was 2.3% at the 15μg/L level.When 0.1‰ triethannolamine was used as masking reagent,the recovery rate was from 94.5% to 97.8%.