四种酸体系溶样法对电感耦合等离子体质谱法测定水系沉积物中16种金属元素的影响

Influence of four sample solution method with acid system on determination of sixteen metal elements in stream sediment by inductively coupled plasma mass spectrometry

敞开酸溶消解方法是测定水系沉积物中金属元素最常用的前处理方法之一,消解时使用不同的酸体系对电感耦合等离子体质谱法（ICP-MS）测定有较大的影响。以水系沉积物标准样品为研究对象,采用5mL硝酸-5mL氢氟酸、5mL硝酸-5mL氢氟酸-2mL盐酸、5mL硝酸-5mL氢氟酸-2mL过氧化氢、5mL硝酸-5mL氢氟酸-2mL高氯酸4种酸体系对样品进行溶解,考察了其对ICP-MS测定16种金属元素（Li、Be、Cr、Mn、Co、Ni、Cu、Zn、Rb、Mo、Cd、Cs、Ba、W、Pb、Bi）结果的影响,并对测定数据进行显著性分析。研究表明：以5mL硝酸-5mL氢氟酸-2mL过氧化氢为消解介质,16种待测元素的回收率均在75%～120%之内;消解水系沉积物的样品时,在5mL硝酸-5mL氢氟酸体系中加上氧化性强的物质可以提高消解效果。考虑到高氯酸中的Cl元素会影响Cr的测定,实验最终选择硝酸-氢氟酸-过氧化氢酸体系进行消解。试验还考察了称样量对测定结果的影响,并也对测定数据进行了显著性分析,最终选择称样量为100mg。在确定的实验条件下对水系沉积物标准物质中16种金属元素进行测定,所得结果与认定值的对数差（ΔlgC）均小于0.13,满足标准DZ/T 0130.5—2006的要求,Bi（认定值为0.03～0.42μg/g）、Ba（认定值为113～681μg/g）、Cd（认定值为0.11～1.38μg/g）和Pb（认定值为23～102μg/g）的相对标准偏差（RSD,n=6）在4.7%～53.0%之间,其他元素的RSD（n=6）均在4.0%～20.5%之间，

The acid digestion in open environment is one of commonly used pretreatment methods for the determination of metal elements in stream sediment.The use of different acid systems has great influence on the determination results by inductively coupled plasma mass spectrometry（ICP-MS）.With the certified reference material of stream sediment as research object,four acid systems were used to dissolve the sample,i.e.,5mL HNO3-5mL HF,5mL HNO3-5mL HF-2mL HCl,5mL HNO3-5mL HF-2mL H2O2,and 5mL HNO3-5mL HF-2mL HClO4.The influence of these four sample dissolution method on the determination of 16 metal elements（including Li,Be,Cr,Mn,Co,Ni,Cu,Zn,Rb,Mo,Cd,Cs,Ba,W,Pb and Bi）by ICP-MS was investigated.Moreover,the significance analysis was conducted based on the measurement data.The results showed that the recoveries of sixteen test elements were between 75%and120% with 5mL HNO3-5mL HF-2mL H2O2 as digestion medium.During the digestion of stream sediment sample,the digestion effect could be improved by adding substance with strong oxidizing ability into5 mL HNO3-5mL HF system.Considering that the Cl in HClO4 would influence the determination of Cr,the HNO3-HF-H2O2 system was adopted.The effect of sample mass on determination results was also investigated.The significance analysis was also conducted based on the measurement data.Finally,100 mg of sample was adopted.16 metal elements in certified reference material of stream sediment were determined under the selected experimental conditions.The logarithm error（ΔlgC）between the results and the certified values were all less than 0.13,which could meet the requirements for standard DZ/T 0130.5—2006.The relative standard deviations（RSD,n=6）for Bi（the certified value of 0.03-0.42μg/g）,Cs（the certified value of 113-618μg/g）,Cd（the certified value of 0.11-1.38μg/g）and Pb（the certified value of 23-102μg/g）were between 4.7% and 53.0%.The RSD（n=6）of other elements were between 4.0% and 20.5%.