超高效液相色谱-串联质谱法测定白芷中51种禁用农药的残留量

将白芷药材粉碎至通过孔径为(250±9.9)μm的网筛,并称取此白芷粉末样品2.00g于聚丙烯管中与水10mL混匀,再加入含1%(体积分数)乙酸的乙腈10.0mL,涡旋1min后加入无水硫酸镁4g和乙酸钠1g,剧烈振荡3min,离心5min,取其上清液5.0mL置于已盛有无水硫酸镁900mg、N-丙基乙二胺(PSA)450mg和硅胶300mg的净化管中,剧烈振荡5min使净化完全,离心5min。移取上清液3.0mL于40℃水浴中减压蒸缩至近干。加入50μg·L^-1的磷酸三苯酯内标溶液300μL,加入乙腈定容至1.0mL,经0.20μm滤膜过滤,取其滤液,按仪器工作条件进行超高效液相色谱-串联质谱法分析。选用Eclipse Plus C18色谱柱和以不同比例的(A)含10mmol·L^-1甲酸铵的0.1%(体积分数)甲酸溶液和(B)乙腈的混合液为流动相,按梯度洗脱程序对白芷中可能残留的51种禁用农药进行色谱分离,并在电喷雾离子源正、负离子(ESI+和ESI-)电离方式和动态多反应监测(dMRM)模式条件下进行串联质谱法测定。采用基质匹配标准曲线法定量。51种农药的质量浓度在一定范围内与其对应的峰面积呈线性关系,并测得其检出限(3S/N)为0.3~5.0μg·kg^-1。标准加入法回收试验的结果显示,其中大部分农药的回收率在71%以上,测定值的相对标准偏差(n=6)均小于20%。按此方法分析了70批白芷样品,共检出16种农药,其中甲拌磷亚砜的检出率达95%,最高检出量为15.2μg·kg^-1;甲拌磷砜和毒死蜱的检出率均为10%,最高检出量依次为3.5,45.0μg·kg^-1,其余13种农药的检出率均低于5%,且检出量均较低。

UPLC-MS/MS Determination of Residual Amounts of 51 Forbidden Pesticides in Roots of Angelica Dahurica

The TCM of root of Angelica dahurica was crushed to pass through sieve with bore of(250±9.9)μm.2.00 g of the powdery sample was taken and after mixing with 10 mL of water it was extracted with 10.0 mL of acetonitrile containing 1%(volume fraction)acetic acid by swirling for 1 min,and then 4 g of anhydr.MgSO4 and 1 g of sodium acetate were added,and the mixture was vibrated vigorously for 3 min.After centrifuging for 5 min,5.0 mL of the supernatant was taken and added to the purification tube in which 900 mg of anhydr.MgSO4,450 mg of PSA and 300 mg of colloidal silica were placed in advance,and the mixture was vibrated vigorously for 5 min to fulfill purification,and after centrifuging for 5 min,3.0 mL of the supernatant was taken and evaporated to near-dryness at 40 ℃ in a water bath under reduced pressure.300μL of 50μg·L^-1 triphenyl phosphate internal standard solution were added into the residue,which was further dissolved and diluted to 1.0 mL with acetonitrile.The solution was filtered through 0.20μm filtering membrane,and the filtrate was used for UPLC-MS/MS analysis under the working condition of the instrument.Eclipse Plus C18 chromatographic column was selected as the stantionary phase and mixtures of(A)0.1%(volume fraction)formic acid solution(containing10 mmol·L^-1 of ammonium formate)and(B)acetonitrile in various ratios were used as mobile phases in programmed gradient elution in the LC separation of the 51 forbidden pesticides,and determined by MS/MS under the condition of ESI+and dMRM.Standard curves were prepared by the mode of matrix matching.Linear relationships between values of peak areas found and the respective mass concentrations of the 51 pesticides were kept in definite ranges.Values of detection limits(3 S/N)were found in the range of 0.3-5.0μg·kg^-1.Recovery was tested by standard addition method,giving values of recovery of most of the 51 pesticides over 71%,and values of RSDs(n=6)found were less than 20%.Substantial samples from 70 batches of the TCM were analyzed by the present method and 16 pectidices were found in these samples.Phorate sulfoxide attained to a high detection rate of 95%,giving highest determined value of 15.2μg·kg^-1.Two other pesticides(phorate sulfone and chlorpyrifos)gave same detection rate of 10%,and their highest determined values were 3.5,45.0μg·kg-1.The remainder13 pesticides all gave detection rates lower than 5% and their determined values were quite low.