ASE-SPE/GC-MS测定土壤中16种PAHs质量控制研究

优化了土壤中16种优控多环芳烃( PAHs)的分析方法,建立了一套完备的质量控制体系,解决了PAHs分析中常见的技术难点,如苯并(a)芘(BaP)回收率低,基质复杂的样品净化效果不理想,萘(Nap)和菲(Phe)挥发损失和环境本底影响等.样品经加速溶剂提取(ASE),固相萃取(SPE)净化,逐级减压浓缩,气相色谱质谱( GC - MS)测定,并以氘代苯并a芘(BaP - d12)作回收率指示物.实验比较了3种正相SPE吸附剂的效果,发现弗罗里硅土对BaP存在明显的降解现象,BaP的定量应使用同位素稀释法,以降低其分析不确定度;氧化铝对PAHs的吸附性过强,不利于样品净化;硅胶最为理想.PAHs的仪器检出限为0.26～5.7 pg,方法检出限为0.067 ～0.97 ng/g(干重),土壤基质加标回收率为71％～ 122％,相对标准偏差为1.6％～8.3％.将该法用于7个电子废物焚烧区域农田土壤样品的测定,PAHs含量在28～ 283 ng/g(干重)之间,样品中BaP-d12的回收率为90％～124％,各项质控指标符合检测要求.

Quality Control on the Determination of 16 PAHs in Soil Using ASE-SPE/GC-MS

The analytical method for 16 USEPA priority polycyclic aromatic hydrocarbons(PAHs) in soil was optimized in this study,and an integrated quality control(QC) system was established to resolve the problems occurring in PAHs analysis,such as the lower recoveries of benzo(a)pyrene(BaP),unsatisfactory clean-up efficiency for samples in complex matrix,volatilization loss and environmental background of naphthalene(Nap) and phenanthrene(Phe).The analysis procedure commenced with accelerated solvent extraction(ASE),followed by solid phase extraction(SPE) clean-up and gradual condensation in vacuum.Gas chromatography-mass spectrometry(GC-MS) was used for measurement.Deuterated benzo(a) pyrene(BaP-d12) was used as an indicator of recovery in analysis.Three normal phase SPE materials were attempted to separate PAHs in samples,the results indicated that BaP was degraded when passing through florisil.Isotope dilution quantification was recommended to reduce the uncertainty of BaP analysis.Alumina was unsuitable for clean up as for its strong adsorption to PAHs,but silica gel was proved to be the appropriate SPE material among the three candidates.The detection limits for the instrument and the analytical method were in the ranges of 0.26-5.7 pg and 0.067-0.97 ng/g(dry weight),respectively.Recoveries of PAHs in spiked soil ranged from 71% to 122%,with RSDs of 1.6%-8.3%.The method was applied in the analysis of 7 farmland soil samples collected from electronic waste combustion area.The concentrations of PAHs were in the range of 28-283 ng/g(dry weight),the recoveries of BaP-d12 ranged from 90% to 124%,which all fell within the acceptable range set by the QC system.