用液质法检测水和土中的草甘膦及草铵膦

Journal of Chromatography A,1081(2005)

145–155

Residue determination of glyphosate,glufosinate and aminomethylphosphonic acid in water and soil samples by liquid

chromatography coupled to electrospray tandem mass spectrometry

Mar´ıa Ib´a˜n ez,´Oscar J.Pozo,Juan V.Sancho,Francisco J.L´o pez,F´e lix Hern´a ndez∗

Research Institute for Pesticides and Water,University Jaume I,E-12071Castell´o n,Spain

Received11February2005;received in revised form3May2005;accepted17May2005

Abstract

This paper describes a method for the sensitive and selective determination of glyphosate,glufosinate and aminomethylphosphonic acid (AMPA)residues in water and soil samples.The method involves a derivatization step with9-fluorenylmethylchloroformate(FMOC)in borate buffer and detection based on liquid chromatography coupled to electrospray tandem mass spectrometry(LC–ESI-MS/MS).In the case of water samples a volume of10mL was derivatized and then4.3mL of the derivatized mixture was directly injected in an on-line solid phase extraction(SPE)–LC–MS/MS system using an OASIS HLB cartridge column and a Discovery chromatographic column.Soil samples were firstly extracted with potassium hydroxide.After that,the aqueous extract was10-fold diluted with water and2mL were derivatized.Then, 50␮L of the derivatized10-fold diluted extract were injected into the LC–MS/MS system without pre-concentration into the SPE cartridge. The method has been validated in both ground and surface water by recovery studies with samples spiked at50and500ng/L,and also in soil samples,spiked at0.05and0.5mg/kg.In water samples,the mean recovery values ranged from89to106%for glyphosate(RSD<9%),from 97to116%for AMPA(RSD<10%),and from72to88%in the case of glufosinate(RSD<12%).Regarding soil samples,the mean recovery values ranged from90to92%for glyphosate(RSD<7%),from88to89%for AMPA(RSD<5%)and from83to86%for glufosinate (RSD<6%).Limits of quantification for all the three compounds were50ng/L and0.05mg/kg in water and soil,respectively,with limits of detection as low as5ng/L,in water,and5␮g/kg,in soil.The use of labelled glyphosate as internal standard allowed improving the recovery and precision for glyphosate and AMPA,while it was not efficient for glufosinate,that was quantified by external standards calibration.The method developed has been applied to the determination of these compounds in real water and soil samples from different areas.All the detections were confirmed by acquiring two transitions for each compound.

©2005Elsevier B.V.All rights reserved.

Keywords:Glyphosate;Glufosinate;AMPA;Water;Soil;Liquid chromatography;Electrospray interface;Tandem mass spectrometry;Derivatization

1.Introduction

Glyphosate[N-(phosphonomethyl)glycine]and glufos-inate[ammonium dl-homoalanin-4-(methyl)phosphinate] are broad spectrum,nonselective,post-emergence herbicides extensively used in various applications for weed control in aquatic systems and vegetation control in non-crop areas. Aminomethylphosphonic acid(AMPA)is the major degra-dation product of glyphosate found in plants,water and soil ∗Corresponding author.Tel.:+34964728100;fax:+34964728066.

E-mail address:hernandf@exp.uji.es(F.Hern´a ndez).[1].Chemical structures of these phosphorus-containing her-bicides are given in Fig.1.

Due to the extensive worldwide use of these compounds and the restrictive regulations for water in the European Union,very sensitive methods for the determination of pes-ticide residues are required.However,the determination of these two herbicides at the sub␮g/L level is difficult due to their ionic character,low volatility,low mass and lack of chemical groups that could facilitate their detection.Even more difficult can result the residue determination in soil at low concentration levels(e.g.below0.1mg/kg),due to the complexity of this matrix sample.Most methods developed

0021-9673/$–see front matter©2005Elsevier B.V.All rights reserved. doi:10.1016/j.chroma.2005.05.041