超声衍生萃取-气相色谱-质谱法测定土壤中茅草枯含量

Ultrasonic Derivatization and Extraction-GC-MS Determination of Dalapon in Soil

以乙二胺四乙酸四钠盐为配位体,五氟苄基溴为衍生剂,取土壤样品(4.0g),石英砂(2g),Na4-EDTA(0.2g)和水1.0mL混匀并放置,使其水分挥发尽后加入丙酮4mL,300g·L-1五氟苄基溴溶液100μL和300g·L-1碳酸钾溶液100μL,进行超声衍生萃取。取上清液1.0mL,吹氮至近干,加入正己烷1.0mL,再次吹氮至近干,定容至1mL,按仪器工作条件进行测定。用HP-5MS毛细管色谱柱进行分离。质谱测定中用负化学离子源。线性范围为2.5~200μg·kg-1,检出限(3S/N)为0.34μg·kg-1。以土壤样品为基体,用标准加入法进行回收试验,测得回收率在89.1%~106%之间,测定值的相对标准偏差(n=7)在9.9%~11%之间。

Sample of soil(4.0g)was mixed with quartz sand(2g),Na4-EDTA(0.2g,as ligand)and water(1.0mL)and the mixture was evaporated to dryness under normal temperature.Acetone(4mL),300g·L-1 pentafluorobenzyl bromide solution(100μL,as derivatizing agent)and 300g·L-1 K2CO3solution(100μL,as catalyst)were added to the mixture,and extraction together with derivatization was carried out ultrasonically.The supernatant(1.0mL)was taken and evaporated to near dryness by N2-blowing.One mL of n-hexane was added and evaporated again to near dryness by N2-blowing.The volume of the n-hexane solution was made up to 1mL,and the GC-MS analysis was carried out as prescribed.HP-5MS capillary column was used in the chromatographic separation,and negative chemical ionization was adopted in MS analysis.Linearity range for dalapon between 2.5-200μg·kg-1 was obtained,with detection limit(3S/N)of 0.34μg·kg-1.Recovery was tested by standard addition method using soil sample as matrix,values of recovery found were in the range of 89.1%to 106%,with values of RSD′s(n=7)ranged from 9.9%to 11%.