Negative electrospray ionization ion mobility spectrometry combined with microextraction in packed syringe for direct analysis of phenoxyacid herbicides in environmental waters

A novel method based on microextraction in packed syringe (MEPS) coupled with negative electrospray ionization-ion mobility spectrometry (ESI-IMS) was developed for simultaneous and direct determination of phenoxyacid herbicides in water samples. The effects of various parameters such as pH of the sample solution, sample loading rate, the nature of elution solvent and its volume, and the number of extraction cycles were investigated. The method was exhaustively validated in terms of sensitivity, recovery, reproducibility, and enrichment factor. The detection limits of the method for 2,4-D, silvex, and haloxyfop were found to be 60, 70, and 90 ng L(-1), respectively. The recovery of the analyzed herbicides was in the range 73-102%, and the relative standard deviation (RSD) was lower than 10% for all the experiments. Various real samples were analyzed with the proposed method, and the obtained results revealed the efficient extraction of the analytes using MEPS extraction before the analysis by negative ESI-IMS.