Analysis of Underivatized Glyphosate and Other Polar Contaminants

Vendor Lunch Speaker
Oral Presentation

Prepared by S. Liang
Restek Corporation, 110 Benner Circle, Bellefonte, PA, 16823, USA


Contact Information: [email protected]; 814-353-1300

ABSTRACT

The most commonly used LC retention techniques for polar compounds are HILIC and ion exchange approaches. The Raptor Polar X is a novel phase chemistry that blends these two mechanisms on a single ligand and provides balanced retention and selectivity for a wide range of polar compounds. In this luncheon seminar, we will discuss how to implement the Polar X column for the analysis of polar contaminants including glyphosate and ultrashort-chain per- and polyfluoroalkyl substances (PFAS) in water.  

The analysis of underivatized glyphosate and its metabolites in water is challenging primarily because it is not retained on reversed-phase columns and its response is often poor due to chelation with metal surfaces along the sample path through the LC-MS/MS system. The Polar X column shows high retention and selectivity for glyphosate, AMPA (glyphosate’s metabolite), and glufosinate as well as other polar pesticides. On a relatively short (3 cm) column and under the simple LC-MS conditions, these structurally related polar compounds are well separated, with a retention k’ for glyphosate, AMPA, and glufosinate being about 30, 4, and 16, respectively. The unique retention mechanism of Polar X column allows large volume injection (500 µL) of drinking water, which is a very simple way to achieve low-level detection of glyphosate at 100 ppt.     

 

Ultrashort-chain (C2 and C3) PFAS are small and very polar compounds including trifluoroacetic acid (TFA), perfluoropropanoic acid (PFPrA), perfluoroethane sulfonate (PFEtS), and perfluoro-propane sulfonate (PFPrS). Their ubiquitous presence in aquatic environment has become a major concern in parallel to PFAS contamination. Given the high polarity of ultrashort-chain PFAS, it is impractical to include these compounds for regular PFAS monitoring with reversed-phase LC. As demonstrated here, a simple and fast LC-MS/MS method was established for simultaneous analysis of ultrashort-chain, alternative, and legacy PFAS in water using the Polar X column.