新污染物PFOS痕量级测定中的影响因素及优化

Factors affecting and modification of the laboratory analysis of PFOS

为解决PFOS浓度测定中的误差问题,开展了PFOS痕量级测定方法的影响因素研究。仪器分析表明:PFOS溶液标准曲线r=0.9988,R^(2)=0.9977,线性关系好,拟合度高;100μg·L^(-1)的PFOS浓度测定允许误差约±6%,平均值置信区间为93.83~105.05μg·L^(-1)。对影响因素的分析表明:PP材质移液枪枪头和玻璃材质注射器均未导致明显系统误差和操作误差;在水与甲醇体积比为1∶9的混合液体系中,PP注射器、PTFE与Nylon滤膜的过滤器均导致PFOS的测定浓度增大,且并非材料中含有PFOS残留所致;以甲醇为溶剂时,PFOS待测液润洗后的PP材质注射器与针式过滤器对PFOS浓度测定无显著影响;以水为溶剂时,PP离心管、PP注射器和针式过滤器对PFOS浓度测定有显著影响,移液枪枪头和玻璃注射器未产生显著影响,故建议使用玻璃容器存放含有PFOS的水样品。液液萃取将水替换甲醇为溶剂,液液萃取操作步骤增多,虽然累积误差增大约1%,但测定精确度高,因此液液萃取具有较好的可行性。

To address the observed errors in PFOS concentration analysis,experiments were carried out to explore factors that influence the analysis of trace-level PFOS concentrations.Instrumental analysis suggested that the statistics of the standard curve of PFOS solution were r=0.9988 and R^(2)=0.9977,indicating that the fitting of the linear relationship is good.The allowable error of 100μg·L^(-1) PFOS concentration was about ±6%,and the average confidence interval was 93.83~105.05μg·L^(-1).Experimental results showed that neither the PP material pipette tip nor the glass material syringe had significant impact.In the experiments with the 1∶9 of water/methanol mixing solution as the solvent,the PP syringe,PTFE and Nylon membrane filters increased the PFOS concentration,which was not caused by the residual PFOS in the materials.In the experiments using methanol as the solvent,the rinsed PP syringes and needle filters had no significant effects on the detection of PFOS.In experiments with pure water as the solvent,PP centrifuge tubes,PP syringes,and needle filters had a significant effect on the analytical results of PFOS concentration,and pipette tips and glass syringes had insignificant effects.Based on the experimental results,we recommend the use glass containers instead of PP ones when collecting water samples.In addition,the analytical results were more accurate for the method with the liquid-liquid extraction,which replaced the aqueous solution with methanol as the solvent,even though the liquid-liquid extraction cumulative error increased by 1% due to extra operation steps.