Shodex advanced HPLC columns has developed a reliable method for the analysis of polar organophosphate-based herbicides.
Introduction
Organophosphate herbicides, such as glyphosate, have been used as weed killers in agriculture for more than four decades. Due to concerns on their toxicity to humans and the environment, which is discussed in several reviews by international health organizations, many countries have set regulations for the maximum allowed concentration levels for a wide range of crops. The European Food Safety Authority (EFSA) and the U.S. Food and Drug Administration (FDA) organizations, for example, therefore, set maximum allowed concentration ranges between 0.1 and 310 ppm (equal to mg/L) depending on the crop type.
HPLC is one of the most effective methods to analyse these compounds. In standard HPLC methods however, these hydrophilic compounds have to be derivatized before injection or ion-pair reagents have to be added to the eluent, to receive sufficient retention in reversed-phase chromatography. These modifications have several drawbacks such as time-consuming sample pretreatment-processes and the increase of the background level from residues on the column and the flow-lines. To improve these circumstances, Shodex advanced HPLC columns has developed a column, i.e., HILICpakTM VT-50 2D, which provides satisfying retention for polar herbicides without additional modification of the analytes and can, therefore, be used for their direct determination.
Results
In this work a reliable method for high-sensitive direct LC/MS/MS simultaneous analysis of six organophosphate herbicide-related compounds including glyphosate and its metabolite, aminomethylphosphonic acid (AMPA); glufosinate and its metabolites, 3-methylphosphinicopropionic acid (MPPA), ethephon, and fosetyl has been developed. The polymer-based column Shodex™ HILICpak™
VT-50 2D was used for this analysis. Due to the hydrophilic packing material of HILICpak VT-50 2D sufficient retention without derivatization of the analytes or use of ion-pair reagents was obtained. With this method a quantification of the target analytes in 1 ppb (equal to μg/L) concentration levels, which meets the criteria of many regulations, is possible.
