In this research, combination of microextraction in packed syringe (MEPS) and negative mode electrospray ionization ion mobility spectrometry (ESI-IMS) was used for the first time for preconcentration and determination of three phenoxyacid herbicides in environmental water samples simultaneously. The MEPS is a novel technique for miniaturized SPE. MEPS is very promising because it is fast, simple and it requires small volume of samples to produce comparable results to conventional SPE technique. MEPS was performed by using 1.4 mg of solid phase material (Oasis HLB) inserted in to a 250 ?L gas-tight syringe. The solid phase material is fixed in the syringe as a plug using polyethylene frits.Sample preparation is performed on the sorbent. Several factors affecting the performance of MEPS such as water sample pH, elution volume, sample loading volume and its speed were studied. Sample pH was adjusted with 0.02 M sulphuric acid at pH=2. In MEPS, sorbent was conditioned first with methanol and then with purified water (2×200 ?L each solvent) before being used for the first time. The water sample (200 ?L in each cycle) was drawn through the syringe and discard in waste (extract–discard) with speed of 2.5 ?L/s. The extraction cycle was repeated 7 times. This step was performed by a variable speed stirring motor which was attached to a circular plate. The solid phase was then washed with 100 ?L purified water to remove interference such as sulphuric acid. The sorbent was dried by a gentle stream of nitrogen gas during 5 minutes. The analytes were then eluted with 20 ?L methanol at speed of 1.0 ?L/s. The eluent was injected directly to ESI/IMS injector. The cleaning of the solid phase was performed using 5×200 ?L methanol then 5×200 ?L purified water. The limits of detection were ranged from 0.04 to 0.08 ?g/L, and the relative standard deviations were under 10%. The applicability of the proposed methods was demonstrated by analyzing spiked real water samples. Recoveries were obtained as higher as 76 to 102%.
