稀酸浸提直接进样测定缢蛏中的镉

Direct sampling detection of cadmium in Sinonovacula constricta using diluted acid extraction

目的 通过正交试验优选出较满意的稀酸浸提前处理方法测定缢蛏中的镉。方法 用稀酸浸泡提取缢蛏中的镉。对稀酸浸提前处理中的固液比、硝酸浓度、混旋时间、浸提温度、浸提时间、超声时间等因素进行二水平的正交试验,用石墨炉原子吸收法对处理过的样液进行测定。同时用湿法消解-石墨炉原子吸收法对上述试验结果进行验证。结果 约0.2 g的缢蛏用0.5%(V/V)硝酸30 ml经2 min混旋,40℃浸提1 h后超声15 min, 10 000 r/min离心5 min是较为满意的前处理方法。其测定结果与经湿法消解前处理的样本的测定结果基本一致。结论 稀酸浸提缢蛏中的镉,操作简便、试剂用量少、耗时短,是较理想的前处理方法,尤其适用于较大样本量缢蛏中镉的测定。

Objective This paper aims to develop a preparative method for the determination of trace cadmium in Sinonovacula constricta using orthogonal test. Methods Cadmium was extracted from Sinonovacula constricta by soaking in dilute acid. Two-level orthogonal test was carried out on solid-liquid ratio, nitric acid concentration, mixing time, extraction temperature, extraction time, and ultrasonic time in the pretreatment of dilute acid extraction. The treated sample was determined by graphite furnace atomic absorption method, and the test results were verified by acid digestion-graphite furnace atomic absorption method. Results About 0.2 g of Sinonovacula constricta were mixed with 30 ml of 0.5%(V/V) nitric acid for 2 minutes, immersed at 40 ℃ for 1 hour, ultrasonicated for 15 minutes, and centrifuged at 10 000 r/min for 5 minutes. The results are basically consistent with those of the samples with pretreatment by wet digestion. Conclusion Dilute acid extraction of cadmium in Sinonovacula constricta is an ideal pretreatment method, which is easy to operate, requires less reagents and takes less time, especially suitable for the determination of cadmium in large batch samples.