建立了一种基于吸力洗脱的流动注射(FI)在线富集与火焰原子吸收光谱法(FAAS)联用测定水样中痕量镉的新方法。洗脱过程依靠蠕动泵的吸力而不是推力实现洗脱剂的输送,明显降低了被分析物在洗脱过程中的分散,提高了原子吸收信号峰值(A),同时提高了富集系数(EF)。进样流速6.0mL/min;进样时间60s,测定20μg/L Cd^2+,EF由传统方法的15提高到38;检出限为0.29μg/L;测样频率为40个/h;相对标准偏差(RSD,n=11)为2.5%。以0.1‰(V/V)的三乙醇胺(TEA)为掩蔽剂,Cd^2+在水样中的回收率为93.8%~98.5%。
A flow injection suction elution method on-line sorption and preconcentration system coupled to flame atomic absorption spectrometry (FAAS) was developed for the determination of trace cadmium in water samples. Compared with conventional elution methods, suction elution process was carried out by the suction of a peristaltic pump. By the suction elution method, the dispersion of the analyte was decreased notably, and high absorbance peak value was achieved. With 60 s ( sample throughput of 40/h) of sampling at a flow rate of 6.0 mL/min, an enrichment factor(EF) of 38 ( higher than 15 achieved by conventional elution method) and a detection limit (3σ) of 0.29 μg/L were obtained. The precision ( RSD, n = 11 ) was 2.5% at the 20 μg/L level. When 0.1%. (V/V) triethanolamine was sued as masking reagent, the recovery was found from 93.8% to 98.5%.