Liquid Chromatography/Electrospray Ionization/Isotopic Dilution Mass Spectrometry Analysis of n-(Phosphonomethyl) Glycine and Mass Spectrometry Analysis of Aminomethyl Phosphonic Acid in Environmental Water and Vegetation Matrixes

Abstract

A liquid chromatography/electrospray/mass spectrometry (LC/ES/MS) method was developed for the analysis of glyphosate (n-phosphonomethyl glycine) and its metabolite, aminomethyl phosphonic acid (AMPA) using isotope-labelled glyphosate as a method surrogate. Optimized parameters were achieved to derivatize glyphosate and AMPA using 9-fluorenylmethyl chloroformate (FMOC-Cl) in borate buffer prior to a reversedphase LC analysis. Method spike recovery data obtained using laboratory and real world sample matrixes indicated an excellent correlation between the recovery of the native and isotope-labelled glyphosate. Hence, the first performance-based, isotope dilution MS method with superior precision, accuracy, and data quality was developed for the analysis of glyphosate. There was, however, no observable correlation between the isotope-labelled glyphosate and AMPA. Thus, the use of this procedure for the accurate analysis of AMPA was not supported. Method detection limits established using standard U.S. Environmental Protection Agency protocol were 0.06 and 0.30 μg/L, respectively, for glyphosate and AMPA in water matrixes and 0.11 and 0.53 μg/g, respectively, in vegetation matrixes. Problems, solutions, and the method performance data related to the analysis of chlorine-treated drinking water samples are discussed. Applying this method to other environmental matrixes, e.g., soil, with minimum modifications is possible, assuring accurate, multimedia studies of glyphosate concentration in the environment and the delivery of useful multimedia information for regulatory applications.

Analysis of glyphosate and aminomethylphosphonic acid in water, plant materials and soil

“…The most commonly practiced preconcentration method for glyphosate and AMPA and/or their derivatization products (see below) has been the use of solid‐phase extraction (SPE) cartridges and disks, such as C18, HLB and anion exchange cartridges . Other less commonly used methods have included preconcentration in vacuo, by heating/evaporation, using supported liquid membranes, lyophilization and large‐volume sample stacking (LVSS) and field‐enhanced sample injection (FESI) . Following enrichment, clean‐up techniques using ligand, anion and cation exchange resins, alone and in combination, as well as chelating resins, have been reported …”

“…7,8,18,29,44,85,98,101,108 -123 Corn, soybean and various forage berry species have also been extracted using water/chloroform, 124 -126 whereas water/methanol (with shaking or sonication) was used for extraction of glyphosate and AMPA from Arabidopsis leaves, maize, peas, barley, flax seed, spinach carrot and straw, 118,127 -129 and water/acetone (with shaking or sonication) was used to extract wheat 97 and Lolium multiflorum. 130 Other less commonly used extractants include water/dichloromethane for various plant samples (wheat, olives, tree leaves, tomato, tobacco, beans, turmeric, chili, coriander, coffee, rice, tea, ginger, blackcurrent, hazelnut); 62,80,114,131,132 water/methanol/dichloromethane for cereals; 129 water/EDTA for guava peel; 96 water/NH 2 silica for AMPA in tomato and water/NaH 2 PO 4 /NH 2 silica for glyphosate in tomato; 133 borate buffer for apple. 134 As with water analyses, the majority of which derivatized glyphosate and AMPA prior to analyses, 75% of the reviewed articles in the past 15 years used derivatization in analyses of plant materials (Table 2).…”

Ultratrace-level determination of glyphosate, aminomethylphosphonic acid and glufosinate in natural waters by solid-phase extraction followed by liquid chromatography–tandem mass spectrometry: performance tuning of derivatization, enrichment and detection

“…Enrichment of glyphosate by solid-phase extraction on an RP cartridge is carried out to obtain an adequate sensitivity for the analysis of natural water samples. Typically, sample volumes of between 4 mL and 50 mL are solid-phase-extracted on C18modified silica gel or polymeric cartridges and the FMOC derivates are detected in positive or negative ion mode [10,11,14]. The most sensitive methods reach a limit of quantification (LOQ) of 50 ng/L for glyphosate in natural waters [10,11].…”

“…Short reaction times and lower temperatures seem to minimize FMOC-OH formation [16,17]. Some studies have used a time-and solvent-consuming liquid-liquid extraction step for the removal of FMOC-OH after derivatization [18,19], while others removed FMOC-OH during the elution from the SPE cartridge using online coupling of the SPE cartridge to the LC column [14,20]. A fast and effective removal step for the by-products in classical offline SPE is still missing.…”

Forty Years with Glyphosate

“…As a result, GC methods remain being used solely due to their analytical parameters, including sensitivity. Nonetheless, LODs of LC and ion chromatographic methods were achieved to be lowered (Mallat & Barceló, 1998;Vreeken, 1998;Bauer et al, 1999;Grey et al, 2001;Patsias et al, 2001;Lee et al, 2002a;Nedelkoska & Low, 2004;Ibáñez et al, 2006;Laitinen et al, 2006;Hanke et al, 2008;Popp et al, 2008) to meet the strictening maximal residue levels (MRLs) in environmental and health regulations. The most recent LC-MS methods using electrospray ionisation (Granby et al, 2003;Martins-Júnior et al, 2011) easily meet the MRL by the EU for given pesticide residues in drinking water, 0.1 µg/l, but the instrumentation demand of these methods is substantial.…”