Skip to Content
Merck
  • Dual element ((15)N/(14)N, (13)C/(12)C) isotope analysis of glyphosate and AMPA by derivatization-gas chromatography isotope ratio mass spectrometry (GC/IRMS) combined with LC/IRMS.

Dual element ((15)N/(14)N, (13)C/(12)C) isotope analysis of glyphosate and AMPA by derivatization-gas chromatography isotope ratio mass spectrometry (GC/IRMS) combined with LC/IRMS.

Analytical and bioanalytical chemistry (2015-05-15)
Emmanuel O Mogusu, J Benjamin Wolbert, Dorothea M Kujawinski, Maik A Jochmann, Martin Elsner
ABSTRACT

To assess sources and degradation of the herbicide glyphosate [N-(phosphonomethyl) glycine] and its metabolite AMPA (aminomethylphosphonic acid), concentration measurements are often inconclusive and even (13)C/(12)C analysis alone may give limited information. To advance isotope ratio analysis of an additional element, we present compound-specific (15)N/(14)N analysis of glyphosate and AMPA by a two step derivatization in combination with gas chromatography/isotope ratio mass spectrometry (GC/IRMS). The N-H group was derivatized with isopropyl chloroformate (iso-PCF), and remaining acidic groups were subsequently methylated with trimethylsilyldiazomethane (TMSD). Iso-PCF treatment at pH <10 gave too low (15)N/(14)N ratios indicating an incomplete derivatization; in contrast, too high (15)N/(14)N ratios at pH >10 indicated decomposition of the derivative. At pH 10, and with an excess of iso-PCF by 10-24, greatest yields and accurate (15)N/(14)N ratios were obtained (deviation from elemental analyzer-IRMS: -0.2 ± 0.9% for glyphosate; -0.4 ± 0.7% for AMPA). Limits for accurate δ(15)N analysis of glyphosate and AMPA were 150 and 250 ng injected, respectively. A combination of δ(15)N and δ(13)C analysis by liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) (1) enabled an improved distinction of commercial glyphosate products and (2) showed that glyphosate isotope values during degradation by MnO2 clearly fell outside the commercial product range. This highlights the potential of combined carbon and nitrogen isotopes analysis to trace sources and degradation of glyphosate.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Phosphoric acid solution, NMR reference standard, 85% in D2O (99.9 atom % D), NMR tube size 3 mm × 8 in.
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid solution, NMR reference standard, 85% in D2O (99.9 atom % D), NMR tube size 5 mm × 8 in.
Pricing and availability is not currently available.
Sigma-Aldrich
N-(Phosphonomethyl)glycine, BioReagent, suitable for plant cell culture
Pricing and availability is not currently available.
Sigma-Aldrich
Diethyl ether
Pricing and availability is not currently available.
Sigma-Aldrich
N-(Phosphonomethyl)glycine, 96%
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid solution, NMR reference standard, 85% in D2O (99.9 atom % D), NMR tube size 4.2 mm × 8 in. , WGS-5BL Coaxial NMR tube
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid solution, 85 wt. % in H2O, FCC, FG
Pricing and availability is not currently available.
Sigma-Aldrich
Isopropyl chloroformate solution, 1.0 M in toluene
Pricing and availability is not currently available.
Sigma-Aldrich
Methanol, NMR reference standard
Pricing and availability is not currently available.
Sigma-Aldrich
Potassium hydroxide, anhydrous, ≥99.95% trace metals basis
Pricing and availability is not currently available.
Sigma-Aldrich
Ethyl acetate
Pricing and availability is not currently available.
Sigma-Aldrich
Ethyl acetate
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid, BioUltra, ≥85% (T)
Pricing and availability is not currently available.
Sigma-Aldrich
Sodium persulfate, BioXtra, ≥99%
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid, BioReagent, suitable for insect cell culture, 85%
Pricing and availability is not currently available.
Sigma-Aldrich
Sodium persulfate, BioUltra, ≥99%
Pricing and availability is not currently available.
Sigma-Aldrich
Potassium phosphate monobasic, BioUltra, for molecular biology, anhydrous, ≥99.5% (T)
Pricing and availability is not currently available.
Sigma-Aldrich
Ethyl acetate, ReagentPlus®, ≥99.8%
Pricing and availability is not currently available.
Sigma-Aldrich
(Aminomethyl)phosphonic acid, 99%
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid, 85 wt. % in H2O, 99.99% trace metals basis
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid, crystalline, ≥99.999% trace metals basis
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid, ≥85 wt. % in H2O, ≥99.999% trace metals basis
Pricing and availability is not currently available.
Sigma-Aldrich
Potassium phosphate monobasic, 99.99% trace metals basis
Pricing and availability is not currently available.
Sigma-Aldrich
Ethyl acetate, natural, ≥99%, FCC, FG
Pricing and availability is not currently available.
Sigma-Aldrich
Ethyl acetate, ≥99%, FCC, FG
Pricing and availability is not currently available.
Sigma-Aldrich
Potassium phosphate monobasic, for molecular biology, ≥98.0%
Pricing and availability is not currently available.
Sigma-Aldrich
Potassium phosphate monobasic, ReagentPlus®
Pricing and availability is not currently available.
Sigma-Aldrich
Potassium phosphate monobasic, powder, suitable for cell culture, suitable for insect cell culture, suitable for plant cell culture, ≥99.0%
Pricing and availability is not currently available.
Sigma-Aldrich
Phosphoric acid-16O4 solution, 70 wt. % in D2O, 99.9 atom % 16O
Pricing and availability is not currently available.
Sigma-Aldrich
Methanol solution, (Methanol:Dimethyl sulfoxide 1:1 (v/v))
Pricing and availability is not currently available.