高效液相色谱法检测土壤时前处理过程对低环多环芳烃损失的影响

Effect of Pretreatment Process on Loss of Low Cyclic Polycyclic Aromatic Hydrocarbons in Soil Detection by High Performance Liquid Chromatography

为降低高效液相色谱法测定土壤样品中萘、苊、苊烯、芴、菲、蒽等6种2~3环多环芳烃和替代物十氟联苯含量时前处理环节造成的损失,优化了前处理条件并探讨了萃取、浓缩、净化对7种目标物回收率的影响。土壤样品用1∶1的丙酮-正己烷混合溶液自动加速溶剂萃取后,所得萃取液在真空度0.06~0.07 MPa、温度30℃下被减压浓缩至5.0 mL,然后在氮气压力100 kPa、温度30℃下被进一步氮吹浓缩至约1.0 mL。若样品需要净化,直接过活化好的Supelco硅酸镁固相萃取柱,用体积比1∶1的二氯甲烷-正己烷混合溶液洗脱。洗脱液(无需净化时为浓缩液)用乙腈置换并稀释至1.0 mL,溶液中的目标物用SUPELCO LC-PAH色谱柱分离,二极管阵列检测器及荧光检测器串联检测,外标法定量。结果显示:采用上述分段浓缩方法可以有效降低目标物的损失;通过分析前处理环节分段模拟液,发现萃取、净化、氮吹浓缩过程对7种目标物回收率的影响较小,减压浓缩过程的影响较大;十氟联苯和6种目标物的质量浓度分别在0.20~10.0 mg·L^(-1),0.04~2.00 mg·L^(-1)内和对应的峰面积呈线性关系,检出限(3.143s)为0.2~2.0μg·kg^(-1);方法用于标准样品的分析,测定值均在认定值的不确定度范围内,测定值的相对标准偏差(n=5)为1.4%~5.7%。

To reduce the loss caused by the pretreatment process in the determination of six 2-3ring polycyclic aromatic hydrocarbons(naphthalene,acenaphthene,acenaphthene,fluorene,phenanthrene,and anthracene)and their substitute,decafluorobiphenyl,in soil sample by high performance liquid chromatography,the pretreatment conditions were optimized and effects of extraction,concentration,purification on the recovery of the 7targets were explored.After automatically accelerating solvent extraction of the soil sample by the mixed solution consisting of acetone and n-hexane at volume ratio of 1∶1,the extract was reduced to 5.0 mL under conditions of vacuum pressure of 0.06-0.07 MPa and temperature of 30℃,and further concentrated to about 1.0mL under conditions of nitrogen pressure of 100kPa and temperature of 30℃.If the sample needed to be purified,the above concentrated solution was directly passed through the activated Supelco magnesium silicate solid phase extraction column,and targets was eluted by the mixed solution composed of dichloromethane and n-hexane at volume ratio of 1∶1.The targets in the eluent(concentration solution when purification was not requided)was displaced into acetonitrile,and the solution was diluted to 1.0mL by acetonitrile.Targets in which were separated by SUPELCO LC-PAH chromatographic column,detected by a diode array detector and a fluorescence detector in series,and quantified by external standard method.It was shown that the segmented concentration method mentioned above could effectively reduce the loss of the targets.By analyzing the segmented simulated solutions in the pretreatment process,it was found that the extraction,purification,and nitrogen blowing concentration processes had a relatively small effect on the recovery of the 7targets,while the vacuum concentration process had a significant effect.Linear relationships between values of the mass concentration and the peak area were kept in the ranges of 0.20-10.0 mg·L^(-1)(decafluorobiphenyl)and 0.04-2.00 mg·L^(-1)(the 6targets),respectively.Detection limits(3.143s)were found in the range of 0.2-2.0μg·kg^(-1).The proposed method was used for analysis of the standard sample,and the determined values were within the uncertainty ranges of the identified values,with RSDs(n=5)of the determined values in the range of 1.4%-5.7%.