微型氢化物发生原子荧光仪简便快速测定稻米中痕量镉

Simple and rapid determination of trace cadmium in rice by miniature hydride generation atomic fluorescence spectrometry

基于自主研发的微型氢化物发生原子荧光仪,建立超声辅助稀酸浸提法简单、快速、准确地测定稻米中痕量镉。通过比较超声、离心、振荡、静置4种辅助浸提方式的稳定性,得到最佳辅助浸提方式;通过单因素实验考察了超声辅助稀酸浸提法中超声时间、超声功率、盐酸浓度、硫脲浓度、镉增敏剂浓度等对镉提取的影响,得到最佳浸提条件。结果表明,超声辅助浸提方式最佳,稳定性最好。最佳浸提条件为:超声时间10 min、超声功率80%、盐酸体积分数4%、硫脲质量浓度5.0 g/L、镉增敏剂质量浓度2.5 g/L。优化后,镉在0.05~0.25 ng/mL范围内线性良好,相关系数为0.999 8,方法检出限为0.000 61 mg/kg,加标回收率为93.3%~106.7%,相对标准偏差为1.62%~4.06%。采用大米标准物质GSB-1和GSB-22进行方法验证,结果准确可靠。与传统方法对比,该方法前处理简单、耗时短、测定准确,适用于稻米中痕量镉的测定。

An ultrasound-assisted dilute acid extraction method for the simple,rapid and accurate determination of trace cadmium(Cd)in rice was established based on the self-developed miniature hydride generation atomic fluorescence spectrometer.The best auxiliary extraction way was obtained by comparing the stability of four auxiliary extraction ways,including ultrasonication,centrifugation,shaking,and resting.The effects of ultrasonic time,ultrasonic power,hydrochloric acid concentration,thiourea concentration,and cadmium sensitizer concentration on the extraction of cadmium were investigated by single-factor experiments to obtain the optimal extraction conditions.Results showed that ultrasound-assisted extraction had the best way and stability.The optimal extraction conditions were as follows:sonication time of 10 min,sonication power of 80%,hydrochloric acid concentration of 4%(volume ratio),thiourea concentration of 5.0 g/L,and cadmium sensitizer concentration of 2.5 g/L.After optimization,the linearity of Cd was good in the range of 0.05-0.25 ng/mL,and the correlation coefficient was 0.9998.The detection limit of the method was 0.00061 mg/kg,the recovery rate was 93.3%-106.7%,and the relative standard deviation was 1.62%-4.06%.The method was verified by rice standard substances GSB-1 and GSB-22,and the results were accurate and reliable.Compared with the traditional method,the method has simple pretreatment,short time consumption,and accurate determination,and is suitable for the determination of trace cadmium in rice.