Evolution of Glyphosate and Polar Pesticides Analysis in Environmental Matrices Using LC/MS/MS

Instrumentation Focus: LCMS
Oral Presentation

Prepared by T. Anumol, J. Roy, J. Grossman
Agilent, 2850 Centerville Rd, wilmington, DE, 19808, United States


Contact Information: [email protected]; 302-636-1517

ABSTRACT

Glyphosate is a synthetic, broad-spectrum herbicide widely used in both agricultural and residential sectors. Glufosinate is naturally produced by plants but is also produced synthetically on an industrial scale. Both are degraded by bacteria in plants, soil and water, to Aminomethylphosphonic acid (AMPA) and 3-(methylphosphinico)propionic acid (MPPA), respectively. The accurate quantitation of these compounds and other polar pesticides (2-hydroxyethyphosphonic acid (HEPA), N-acetylglufosinate, Ethephon, Fosetyl) at low ng/L levels in surface water, and low-ug/L levels in other matrices, have proven to be challenging, given their very polar nature. Traditionally, the analysis of Glyphosate and AMPA has been performed using a derivatization process and either GC/MS or later LC/MS/MS. While the method is sensitive, the derivatization is time-consuming, laborious and also not environmentally friendly. This has driven demand for direct analysis of polar pesticides with the increase in sensitivity of LC/Ms/Ms instrumentation that allow the required detection limits along with better reproducibility and reproducibility. A simple yet effective methodology was developed that includes quick sample preparation, very robust reversed-phase chromatography and sensitive mass spectrometry detection for routine analysis. An innovative method using a new superficially porous reversed phase LC column, which excels at retaining difficult polar molecules was used for robust analysis and good seperation. In contrast to HILIC approach, this method allows for a larger injection volumes of the 100% aqueous extracts allowing no need for organic solvent exchange for water samples, resulting in lower detection limits without sacrificing peak shape. The peak shape of all studied compounds remained stable throughout multiple matrices, even though a large injection volume is used and the pesticides are not derivatized. The retention times and peak areas are very reproducible across all studied matrices including drinking water, surface water, wine, and honey , even in the ng/L range, indicating that the overall strategy is insensitive to matrix. Further, comparison will be shown against a derivatization LC/MS/MS process with pros and cons for each technique.