固体进样-电热蒸发-原子吸收法测定土壤中的镉

采用固体进样原子吸收法直接测定土壤中的镉,可以避免传统酸消解预处理过程耗时长、试剂消耗大、操作步骤繁琐等缺点,提升镉的检测效率。通过优化测镉仪的仪器参数,确定了固体进样-电热蒸发-原子吸收法的优化仪器条件。采用优化条件测定了不同浓度的土壤样品,研究了该方法的检出限、正确度、精密度。研究结果表明:镉质量范围为0~200 ng时与峰面积的线性相关系数优于0.999 5,空气流下优化的灰化温度和热解温度均为800 ℃,优化的热解气体氢气流量为300 mL/min,当样品进样量为0.1 g时,检出限为0.009 mg/kg,7次连续测定相对标准偏差为1.4%~5.0%,加标回收率为96.2%~102.1%,分析时间小于4 min。该方法操作简便,用时短,无需高压气源,可以用于土壤中镉的高效检测。

Determination on Cadmium in Soil Sample by Electrothermal Vaporization-Atomic Absorption Spectrometry

Compared with traditional method for detection of cadmium(Cd) which needs acid digestion, solid sampling electrothermal vaporization atomic absorption spectrometry could improve Cd detection efficiency and avoid time-consuming, reagent consumption and cumbersome operation steps. By optimizing the instrument parameters of Cd detection instrument, the optimal instrument conditions of solid injection electrothermal evaporation atomic absorption spectrometry were determined. Soil samples with different concentrations were determined under optimized conditions, and the detection limit, trueness and precision of the method were studied. The results suggested that the linear correlation coefficient of Cd mass and peak area in the range of 0-200 ng was better than 0.9995. The optimal ashing temperature and furnace temperature under air flow were both 800 °C and the hydrogen flow rate was 300 mL/min. The optimal mass of sample injection was 0.1 g and the detection limit was 0.009 mg/kg. Meanwhile, the relative standard deviation was 1.4%-5.0% for 7 consecutive measurements with recovery of 96.2%-102.1%, and the analysis time was less than 4 minutes. The method possess advantages of simple operation, short-time analysis and unrequirement of high-pressure air supply, which would be widely used in effective detection of Cd.