全自动消解-电感耦合等离子体质谱(ICP-MS)法测定海洋沉积物中重金属

Determination of Heavy Metals in Marine Sediments by Inductively Coupled Plasma Mass Spectrometer with Automatic Digestion

目前海洋沉积物前处理主要通过电热板消解,但该方法存在消解不完全、前处理时间长、重复性较差以及手工消解操作繁琐等问题。为提高海洋沉积物中重金属消解效率,通过考察硝酸、盐酸、氢氟酸和高氯酸组合酸体系比例和最高消解温度对海洋沉积物预处理的影响,确定了最优的消解条件,建立了全自动消解-电感耦合等离子体质谱(ICP-MS)法测定海洋沉积物中重金属的方法。结果显示,硝酸占比越高各元素消解效果越好,盐酸用量不宜过多,逆王水消解比例最好。最优预处理条件为9 mL硝酸、3 mL盐酸、4 mL氢氟酸和2 mL高氯酸于160℃高温消解,所得曲线各元素相关性系数均大于0.999,经海洋沉积物标准样品(GBW07314)和实际样品的验证,与国家标准方法(GB/T 20260—2006)相比,优化条件下各元素精密度和正确度均显著提高、检出限更低。各元素的相对标准偏差为0.50%~3.4%,加标回收率均在84.2%~102%。方法自动化程度高、操作简便,可实现大批量样品预处理,适用于海洋沉积物中重金属元素的测定。

At present,the pretreatment of marine sediments is mainly processed by electric heating plate digestion,but this method has some problems,such as incomplete digestion,long pretreatment time,poor repeatability and tedious manual digestion operation.In order to improve the efficiency of heavy metal digestion in marine sediments,the optimal digestion conditions were determined by investigating the effects of the ratio of nitric acid,hydrochloric acid,hydrofluoric acid and perchloric acid combined acid system and the maximum digestion temperature on the pretreatment of marine sediments,and a method for the determination of heavy metals in marine sediments by automatic digestion and inductively coupled plasma mass spectrometer was established.The results showed that the higher the proportion of nitric acid,the better the digestion effect of each element,and the dosage of hydrochloric acid should not be too much.The optimal pretreatment conditions were 9 mL nitric acid,3 mL hydrochloric acid,4 mL hydrofluoric acid and 2 mL perchloric acid digestion at 160℃.The correlation coefficients of each element under the pretreatment conditions were greater than 0.999.After the application of marine sediment standard sample(GBW07314)and actual sample,compared with the national standard method(GB/T 20260—2006),the precision and accuracy of each element under the optimized conditions were significantly improved and the detection limit was lower.The relative standard deviations of each element were 0.50%—3.4%,the recoveries were 84.2%—102%.The method is of high automation and simple operation,which can realize mass sample pretreatment and is suitable for the determination of heavy metal elements in marine sediments.