采用GC-ECD和GC-MS分别测定并比较甘草锌颗粒及复心片中二十种有机氯农药残留量

Determination of 20 organochlorine pesticide residues in Gancaoxin Granule and Fuxin Tablet by GC-ECD and GC-MS respectively and comparisons between the two methods

目的:探索并比较2种中成药中20种有机氯农药残留量的GC-ECD和GC-NCI-MS测定方法。方法:采用固定相萃取净化杂质,DB-1701MS和HP-5MS弹性石英毛细管柱分离待测组分,ECD和NCI-MS分别检测。进样口温度:230℃,载气:N2(99.99%,ECD)和He2(99.999%,MS),柱流量:1.0 mi/min,不分流进样,进样量:1μL;ECD温度300℃;MS选择化学电离负离子源,离子源温度:200℃,电离能量:100 eV,传输管温度:290℃,反应气为甲烷,流量:3.0 mL/min,以全扫描方式(scan)定性,选择离子(SIM)方式定量。结果:20种有机氯在2根毛细管柱上不可能通过调整升温程序来达到全部分离,最多可检测到19个峰,在DB-1701柱上,甲基五氯苯硫醚和艾试剂重叠(ECD),氧氯丹和δ-666重叠(MS),而在HP-5柱上,环氧七氯和氧氯丹重叠,重叠的二成分采用ECD检测无法定量;而用MS检测则可通过寻找一定丰度的不同质荷比特征离子(如氧氯丹中316m/z和δ-666中255m/z),采用选择离子方式(SIM)而同时分别定量。此外,除六氯苯、反氯丹、pp’-DDE和异狄试剂外,二种制剂中的20种有机氯残留的MS数据普遍比ECD低,定量限普遍比ECD高。结论:GC-ECD法对于痕量级的农药残留检测具有灵敏度高和精密度好的优势,但定性和定量均易受假阳性及背景的干扰;而GC-MS法定性专属,定量也不受干扰,但检测灵敏度和精密度均不及ECD。因此,对于本试验中20种有机氯的测定,GC-MS法具有快速、准确性强的优势,而GC-ECD法则具有灵敏度高、精密度好的优势。

AIM： To investigate the differences between GC-ECD and GC-MS methods which were employed in the determination of 20 organochlorine pesticide residues in Gancaoxin Granule （Radix et Rhizoma glycyrrhizae, zine preparation） and Fuxin Tablet （Folium Crataegi）. METHODS： The solid-phase extraction was used for the clean-up of samples, the quartz capillary columns of DB-1701MS and HP-SMS were selected for the separations of target pesticides, ECD and MS were introduced as the detections respectively. N2 （99. 99%, ECD ） and He2 （99. 999% ,MS） were used as carries, a column flow was at 1.0 mL/min, splitless was chosen as injection mode, injection amount was 1 uL for all instances, the inlet was set at 230 ℃ and ECD at 300 ℃, negative ions-chemical ionization was used as ion source in MS, the source temperature was set at 200 ℃, the electron energy was at 100 eV, and the temperature of transfer line was at 290 % ; methane was used as reagent gas with a flow of 3.0 mL/ min, scan mode was for qualification, SIM mode was for quantitation. RESULTS： Because 20 organochlorine pesticides were impossible to be separated all on single column by an optimal temperature program to present maximum 19 peaks, on HP and column, both heptachlor-epoxide and oxy-chlordane appeared as a peak, while the overlaid peak in DB-1701 column was contributed by eicher pentachlorothioanisole and aldrin in ECD or oxy-chlordane and δ-666 in MS. We selected SIM mode in MS detection with different m/z and abundance to quantify. By a comparison, the residues of 20 organochlorine pesticides in two preparations showed higher in ECD than that in MS, except for hexachlorobenxene, trans-chlordane, pp＇ -DDE and endrin, the LOQs of 20 insecticides in ECD was commonly lower than that in MS. CONCLUSION： The ECD method has an advantage in sensitivity and precision, but its result on either qualification and quantitation is prone to the interferences of false positive peaks and background; while MS detection has high specificity in qualification and good accuracy in quantitation, but lower sensitivity and precision compared to ECD. Therefore, GC-ECD method for 20 organochlorine pesticide residues is sensitive and of good precision, while GC-MS method is rapid and accurate.