Determination and Quantification of Folpet in Barley using HPLC-DAD Analysis

Abstract

Although rоutinе pesticide analysеs are mostly performed using GC-MS, GC-MS/MS and/or LC-MS/MS, some pesticides especially those with relatively high MRLs and good detector response could also be precisely quantified with less sensitive equipment which gives the opportunity to some laboratories to expand their scope of work. The study focuses on HPLC-DAD method development for detection of folpet in barley grain. QuEChERS method was performed for extraction after which, additional clean-up was performed using PSA and polypropylene filtration. Pesticide separation was achieved using mobile phase of acidified CAN (pH 2.5) and water. The initial mobile phase was 60:40% (v/v), the elution gradient starts from 80:20% (v/v) to 100:0% (v/v) in 7 min and holds 100:0% (v/v) up to 8.5 min at a flow rate of 1 ml/min after which in the next 6.5 min the column was re-equilibrated to 40% phase-B.

Calibration was performed using matrix-matched calibration standards. The obtained limits of detection (LOD) and quantification (LOQ) were 0.18 and 0.55 mg/kg, respectively, and the linear regression coefficient was 0.9973. Recovery, repeatability and  reproducibility were investigated at three fortification levels (0.1 mg/kg, 0.6 mg/kg, and 1.6 mg/kg) and were found acceptable with relative standard deviation less than 10%. The method was applied for the analysis of three barley grain samples obtained from different producers and showed that folpet was present in one sample below the LOQ. Overall, the developed method is suitable for the determination of folpet in barley grains at levels below the established MRL of 1 mg/kg.