Direct Determination of Glyphosate and Its Major Metabolite, Aminomethylphosphonic Acid, in Fruits and Vegetables by Mixed-Mode Hydrophilic interaction/weak Anion-Exchange Liquid Chromatography Coupled With Electrospray Tandem Mass Spectrometry

J Chromatogr A. 2013 Jan 11;1272:90-9. doi: 10.1016/j.chroma.2012.11.069. Epub 2012 Dec 3.

Abstract

A novel method was developed for the direct, sensitive, and rapid determination of glyphosate and its major metabolite, aminomethylphosphonic acid (AMPA), in fruit and vegetable samples by mixed-mode hydrophilic interaction/weak anion-exchange liquid chromatography (HILIC/WAX) coupled with electrospray tandem mass spectrometry (ESI-MS/MS). Homogenized samples were extracted with water, without derivatization or further clean-up, and the extracts were injected directly onto the Asahipak NH2P-50 4E column (250 mm × 4.6 mm i.d., 5 μm). The best results were obtained when the column was operated under mixed-mode HILIC/WAX elution conditions. An initial 10-min washing step with acetonitrile/water (10:90, v/v) in HILIC mode was used to remove potentially interfering compounds, and then the analytes were eluted in WAX mode with acetonitrile and water containing 0.1 molL(-1) ammonium hydroxide under gradient elution for the ESI analysis in negative ion mode. Limits of quantification of glyphosate and AMPA were 5 μgkg(-1) and 50 μgkg(-1), respectively, with limits of detection as low as 1.2 μgkg(-1) for glyphosate and 15 μgkg(-1) for AMPA. The linearity was satisfactory, with correlation coefficients (r)>0.9966. Recovery studies were carried out on spiked matrices (6 vegetables, 3 fruits) with glyphosate at four concentrations and AMPA at three concentrations. The mean recoveries for glyphosate and AMPA were 75.3-110% and 76.1-110%, respectively, with relative standard deviations in the range of 1.1-13.8%. The intra-day precision (n=7) for glyphosate and AMPA in vegetable and fruit samples spiked at an intermediate level between 5.9% and 7.5%, and the inter-day precision over 11 days (n=11) was between 7.0% and 13%.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calibration
  • Chromatography, Liquid
  • Environmental Monitoring
  • Fruit / chemistry*
  • Glycine / analogs & derivatives*
  • Glycine / analysis
  • Glycine / metabolism
  • Hydrophobic and Hydrophilic Interactions*
  • Ion Exchange
  • Isoxazoles
  • Limit of Detection
  • Organophosphonates / analysis*
  • Reference Standards
  • Solutions
  • Spectrometry, Mass, Electrospray Ionization / methods*
  • Tandem Mass Spectrometry / methods*
  • Tetrazoles
  • Vegetables / chemistry*

Substances

  • Isoxazoles
  • Organophosphonates
  • Solutions
  • Tetrazoles
  • glyphosate
  • 2-amino-3-(3-hydrox-5(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl)propionic acid
  • Glycine