碱性溶液微波消解-氢化物发生-原子荧光光谱法测定土壤中锡

土壤样品先在烘箱内于(102±3)℃下干燥2h。称取此样品0.10g置于聚四氟乙烯(PTFE)消解罐中,加入500g·L^-1氢氧化钠溶液2mL,按程序升温模式在微波消解仪中进行消解。消解完成后,加二次去离子水将溶液稀释至25.0mL,样品溶液经载流(1mol·L^-1氢氧化钠溶液)通过三通阀进入仪器,并在线被5%(体积分数)硫酸溶液中和后与由蠕动泵传送的还原剂硼氢化钾反应生成氢化锡,传送进入原子化器迅速原子化,在高性能空心阴极灯的作用下产生荧光,由检测器检测其峰面积。测得锡的标准曲线的线性范围在100μg·L^-1以内。以3倍空白值求得的标准偏差计算其检出限(3s)为0.062μg·g^-1。用此方法测定了7个GBW标准物质,所得结果与认定值之间的相对误差为-1.61%~3.07%,测定值的相对标准偏差(n=7)为1.8%~3.2%。

Determination of Tin in Soil by Hydride Generation-Atomic Fluorescence Spectrometry with Microwave Assisted Digestion in Alkaline Solution

The soil sample should be dried preliminarily at(102±3)℃in an oven.0.10g of the dried sample was taken and digested with 2mL of 500g·L-1 sodium hydroxide solution in the PTFE vessel in the microwave digestor under programmed temperature elevation mode.At the end of digestion,the solution obtained was diluted to 25.0mL with re-deionized water,and used as sample solution for atom fluorescence spectrometry analysis.The sample solution was introduced into the atom fluorescence spectrometry instrument by the carrier of 1mol·L^-1 sodium hydroxide solution and through the 3-way valve.5%(volum fraction)sulfuric acid solution,as introduced also through the 3-way valve,was used for online neutralization of the alkaline sample solution,and then the acidic sample solution was reacted with potessium borohydride,delivered by the wriggling pump,to have the Sn(Ⅱ)reacted to form tin hydride which was atomized in the atomizer.By the action ofthe high performance hollow cathode lamp,fluorescence of tin atom was emitted and its intensity as shown by its peak area was measured by the detector.Linearity range of the standard curve of tin was found within 100μg·L^-1.Value of detection limit(3s)found was 0.062μg·g^-1.Seven GBW standard materials of soil were analyzed by the present method,giving relative errors between the results found by this method and the certified values of the CRMs in the range of-1.61%-3.07%.Values of RSDs(n=7)obtained were ranged from 1.8%-3.2%.