Optimization and Selection of Mobile Phase for the Determination of Multiple Pesticide Standards Using Liquid Chromatography-Tandem Mass Spectrometry

Abstract

The selection of the best mobile phase setup is one of the most important factors to beconsidered prior to quantitative instrumentation of multiple pesticides. Usually, mobile phases comprises ofwater (A) and an organic solvent (B) are the setup used in liquid chromatography instruments for theanalysis of pesticide residues in various samples. Unfortunately, most of the analyses are being carried outwithout optimization and selection of the best mobile phase setup to improve the sensitivity of theinstrument. For that reason, the comparative analysis of the reportedly used mobile phases and some fewsuggested ones was carried out on the multi-pesticide mixture of 0.1 mg/kg (100 µg/kg) standard solutionsand quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS) instrument.Consequently, the best mobile phases setup that resulted in the sum of average total chromatographic peakareas (ATCPAs) and average total chromatographic peak heights (ATCPH) for the total ion chromatography(TIC) scans as an index that correspond to the concentration levels was selected [0.1% formic acid in H2O(A) and 0.1% formic acid in acetonitrile (ACN) (B)]. And further optimization was successfully carried out onthe selected mobile phase-A and the resulted setup [1% ACN and 0.1% formic acid in Milli-Q-water (mobilephase A) coupled with 0.1% formic acid in ACN (mobile phase-B)] improved the instrumental sensitivity onthe targeted analytes. Thus, this justify the potential benefits of optimizing setup of the mobile phases priorto LC-MS/MS instrumentation of multi-pesticide analytes.