Taguchi V Y, Jenkins S W, Crozier P W, Wang D T
Ministry of the Environment, Laboratory Services Branch, Etobicoke, Ontario, Canada.
J Am Soc Mass Spectrom. 1998 Aug;9(8):830-9. doi: 10.1016/S1044-0305(98)00043-9.
A method for the determination of the herbicides diquat and paraquat in water was developed using liquid chromatography-(electrospray ionization) mass spectrometry [LC-(ESI)MS]. The analytes were isolated on an ENVI-8 DSK solid phase extraction (SPE) disk and eluted with 5-M trifluoroacetic acid (TFA). The eluate was evaporated to dryness and the analytes were redissolved in the mobile phase (7% methanol/93% water/25-mM TFA). The extract was analyzed by liquid chromatography (C1 column) with postcolumn addition of propionic acid/methanol followed by (ESI)MS. Diquat was detected using the [M(2+)-H+] ion (M2+ = dication) at m/z 183, whereas paraquat was detected using the mono-trifluoroacetate ion pair [M2 +/- OOCCF3] at m/z 299. Quantitation was done by isotope dilution mass spectrometry using d4-diquat and d8-paraquat and the corresponding ions [M(2+)-D+] and [M2 +/- OOCCF3] at m/z 186 and m/z 307, respectively. Detection limits of 0.1 and 0.2 microgram/L, respectively (based on the dications), were adequate to meet the Ontario Drinking Water Objectives of 70 and 10 micrograms/L, respectively, and the Ontario Provincial Water Quality Objective for diquat of 0.5 microgram/L. Precision and accuracy were 14% and 6% for diquat and 12% and 3% for paraquat.
建立了一种使用液相色谱 -（电喷雾电离）质谱法[LC -（ESI）MS]测定水中除草剂敌草快和百草枯的方法。分析物在ENVI - 8 DSK固相萃取（SPE）盘上进行分离，并用5 - M三氟乙酸（TFA）洗脱。洗脱液蒸发至干，分析物重新溶解于流动相（7%甲醇/93%水/25 - mM TFA）中。提取物通过液相色谱（C1柱）进行分析，柱后加入丙酸/甲醇，随后进行（ESI）MS分析。敌草快通过质荷比为183的[M(2 +)-H+]离子（M2 + = 二价阳离子）进行检测，而百草枯通过质荷比为299的单三氟乙酸离子对[M2 +/- OOCCF3]进行检测。采用d4 - 敌草快和d8 - 百草枯以及相应的质荷比分别为186和307的离子[M(2 +)-D+]和[M2 +/- OOCCF3]，通过同位素稀释质谱法进行定量分析。检测限分别为0.1和0.2微克/升（基于二价阳离子），足以分别满足安大略省饮用水目标中70和10微克/升的要求，以及敌草快安大略省省级水质目标0.5微克/升的要求。敌草快的精密度和准确度分别为14%和6%，百草枯的精密度和准确度分别为12%和3%。
