title: 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.
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%.
authors.affiliation: China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: Ming-Xue
authors.initials: MX
authors.lastname: Chen
authors.forename: Zhao-Yun
authors.initials: ZY
authors.lastname: Cao
authors.forename: Yan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Zhi-Wei
authors.initials: ZW
authors.lastname: Zhu
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid; D004784:Environmental Monitoring; D005638:Fruit / Q000737:chemistry*; D005998:Glycine / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D007474:Ion Exchange; D007555:Isoxazoles; D057230:Limit of Detection; D063065:Organophosphonates / Q000032:analysis*; D012015:Reference Standards; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013777:Tetrazoles; D014675:Vegetables / Q000737:chemistry*; D000097797:Glyphosate
chemical_list: D005998:Glycine; D007555:Isoxazoles; D063065:Organophosphonates; D012996:Solutions; D013777:Tetrazoles; D000097797:Glyphosate; C418233:2-amino-3-(3-hydrox-5(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl)propionic acid