13C- and 15N-Isotope Analysis of Desphenylchloridazon by Liquid Chromatography–Isotope-Ratio Mass Spectrometry and Derivatization Gas Chromatography–Isotope-Ratio Mass Spectrometry

• DOI: 10.1021/acs.analchem.8b04906
• Publication Date: 2019-01-24T17:01:16Z
• Authors: Aileen Melsbach; Violaine Ponsin; Clara Torrentó; Christina Lihl; Thomas B. Hofstetter; Daniel Hunkeler; Martin Elsner
• Keywords: Isotope-ratio mass spectrometry; Isotopes of chlorine; Carbon-13

The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent even more polar than the parent herbicide, which increases risk groundwater contamination. When are still applied, metabolites constantly formed also degraded. Evaluating their degradation on basis concentration measurements is, therefore, difficult. This study presents compound-specific stable-isotope analysis (CSIA) nitrogen- carbon-isotope ratios at natural abundances as an alternative analytical approach to track origin, formation, (DPC), major product herbicide chloridazon. Methods were developed validated for carbon- nitrogen-isotope (δ13C δ15N) DPC by liquid chromatography–isotope-ratio mass spectrometry (LC-IRMS) derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standards directly onto Atlantis LC-column resulted in reproducible δ13C-isotope (standard deviation <0.5‰) LC-IRMS with a limit precise 996 ng on-column. Accurate δ15N standard <0.4‰ was achieved GC-IRMS after >100 160-fold excess (trimethylsilyl)diazomethane. Application method environmental-seepage indicated that newly could distinguished "old" different isotopic signatures two sources.