基于直接进样-超高效液相色谱串联质谱法的水中2甲4氯残留测定

Determining 4-chloro-2-methylphenoxyacetic acid residue in waters via direct injection-UPLC-MS/MS

针对目前水体中MCPA检测灵敏度不够,缺乏一种无需前处理、可直接上机、简单便捷方法的问题,以超高液相色谱串联质谱仪,建立了一种以电喷雾离子源ESI-为电离模式、MRM为监测模式、可直接进样测定水体中MCPA残留的方法。结果表明,最优方法条件为定量离子对199.0/140.9(m/z),流动相乙腈和水梯度洗脱,色谱柱Acquity UPLC HSS T3。在MCPA质量浓度为0.1~100μg/L范围内线性良好(R2=99.99%),检出限为0.006μg/L,定量限为0.018μg/L,是现有直接进样法的23~83倍,完全满足水体中MCPA的检测要求(<0.1μg/L)。在添加水平为1~100μg/L时,回收率为94.30%~105.60%,相对标准偏差为1.05%~3.61%,具有前处理简单、准确性高、精密度好、灵敏度高等优点。

The present paper is inclined to devote itself to the study of 4-chloro-2-methylphenoxyacetic acid( MCPA),one of the high toxic herbicides that may cause potential environmental risks for waters. For the said purpose,the paper has developed a simple and sensitive ultra-performance liquid chromatographytandem mass spectrometry to analyze the MCPA residue in the corresponding waters by way of electrospray ionization and the multiple reaction monitoring mode( MRM),and then to execute the direct injection in priority. Through the above said methodological analysis,the paper has successfully established a series of optimal parameters,including the chromatographic condition parameters and the mass spectrum ones. Besides,since it is easy for the MCPA to get dissociated to form anion,the paper has also adopted a kind of negative electrospray ionization(ESI-) with the best quantification ion pair of 199. 0/140. 9 m/z. And,furthermore,the mobile phase has been done to isolate MCPA from the impurities containing acetonitrile and ultrapure water under the gradient elution. And,next,acuity of the UPLC HSS T3 column has been chosen as the chromatographic column to improve thesensitivity of the method via the specific force between its exposed silanol groups and the anionic MCPA. And,later,a step further has been taken to realize the stable sampling performance to gain great volumes of 10 μL for injection. Hence,as a result,it has been made possible to obtain the excellent linear relationship between the chromatographic peak area(y) and the mass concentration rate( x) of MCPA in the range of 0. 1-100 μg/L via the linear equation of y = 13741 x-7247. 7(R2= 99. 99%).Furthermore,the detection limit and the quantitation limit have been found sensitively known as the amounts of 0. 006 μg/L and0. 018 μg/L,respectively. Additionally,the actual limit of LOD has been worked out at about 23-83 times as much as the result gained with the currently existing direct injection method so as to satisfy the detective demands of MCPA fully in the waters at a rate less than 0. 1 μg/L. And,so,under the fortified level of 1-100 μg/L MCPA,the relative recovery rate of MCPA has been found in the lake water and drinking water up to the range of94. 30%-105. 60% with the relative standard deviation between the ratios of 1. 05%-3. 61%. Thus, consequently, the said method proves to help to dissolve the contradiction between"the column retention " and "the mass spectrometry ionization " of MCPA. And,in turn,the method has also been recognized to be simple,quick,accurate and sensitive,as well as suitable for analyzing the trace MCPA residues in the corresponding waters.