自动固相萃取法联合液相色谱-串联质谱法测定稻田水中7种常用农药的残留量

Determination of Residues of 7 Commonly Used Pesticides in Paddy Water by Liquid Chromatography-Tandem Mass Spectrometry Combined with Automatic Solid Phase Extraction

随机收集稻田水样,挑去漂浮物,分取1 000mL,将其酸度调至中性。分取500mL上述水样,以流量12mL·min-1过活化好的HLB固相萃取柱,用15mL体积比2∶1的丙酮-环己烷混合溶液洗脱。收集洗脱液,于45℃氮吹至近干,加入1mL乙腈溶解残渣,供液相色谱-三重四极杆串联质谱仪分析。色谱分析中,以YMC sphere ODS C18色谱柱作固定相,以不同体积比的甲醇和0.1%(体积分数)甲酸溶液的混合溶液作流动相进行梯度洗脱。在质谱(MS)分析中,以电喷雾离子源正离子(ESI+)模式电离,以多反应监测(MRM)模式检测。结果表明,噻嗪酮、吡虫啉、多菌灵、三环唑、稻瘟灵、苄嘧磺隆、乙草胺等7种农药的质量浓度均在0.01~4.00mg·L^(-1)内与对应的峰面积呈线性关系,检出限(3S/N)为0.006~0.028μg·L^(-1)。对空白水样进行3个浓度水平的加标回收试验,回收率为85.2~103%,测定值的相对标准偏差均小于5.0%。

Paddy water samples were randomly collected,floating debris in which was removed.An aliquot(1000 mL)was taken,and its acidity was adjusted to neutral.An aliquot(500 mL)of the above water sample was taken and passed through the activated HLB solid phase extraction column at flow rate of 12 mL·min^(-1),and elution was made with 15 mL of acetone-cyclohexane mixed solution at volume ratio of 2:1.The eluate was collected,and blown to near dryness by nitrogen at 45℃.Acetonitrile of 1 mL was added to dissolve the residue,and the mixed solution was analyzed by liquid chromatograph-triple quadrupole tandem mass spectrometer.In chromatographic analysis,YMC sphere ODS Cis chromatographic column was used as the stationary phase,and mixtures composed of methanol and o.1%(volume fraction)formic acid solution at different volume ratios were used as the mobile phase for gradient elution.In the MS analysis,the ESI+mode was used for ionization,and the MRM mode was used for detection.It was shown that linear relationships between values of the mass concentration and the corresponding peak area of 7 pesticides including thiazinone,imidacloprid,carbendazim,tricyclazole,isoprothiolane,bensulfuron methyl and acetochlor,were kept in the same range of 0.01-4.00 mg·L^(-1),with detection limits(3S/N)in the range of 0.006-0.028μg·L-1.The spiked recovery test was conducted on blank water samples at the 3 concentration levels,giving recoveries ranging from 85.2%to 103%,and RSDs of the determined values were less than 5.0%.