Determination of Trace Amount of Methyl Parathion Using In Situ Solvent Formation Microextraction Method (ISFME) Based on Ionic Liquids in Aqueous Samples by GC-FID

A simple, green, precise, and sensitive method to determine trace amounts of Methyl parathion in aqueous solutions was used. In situ solvent formation microextraction based two components solvent system containing organic and aqueous phases. The organic phase contains hydrophilic ionic liquid namely 1-hexyl-3-methylimidazolium chloride [Hmim][Cl] and the aqueous phase contains an analyte of Methyl parathion. After mixing of two phases, the maximum mass transfer of the analyte from aqueous to organic phase was occurred and finally separation of phases use counter ion namely lithium bis(trifluoromethansulfonyl) imide. By adding of counter ion, hydrophilic ionic liquid [Hmim][Cl] caused anion exchange converted to hydrophobic ionic liquid [Hmim][NTF2] and phase separation was possible. Analyte enriched in organic phase after thermal desorption by using gas chromatography-flame photometry detection was determined. Effective parameters on extraction such as pH of the aqueous phase, amounts of ionic liquid, and the amount of counter-ion was evaluated and optimized. Figures of merit such as precision in the form of percent Relative Standard Deviation (RSD) for 7 replicate measurements equal to 1.2%, quantity Limit of Detection (LOD) of 0.39 µg/L, enrichment factor of 125, and linear range of 10-150 µg/L were obtained. Finally, the method was used successfully to determine amounts of methyl parathion in different aqueous and saline samples.