The main aim of this research is to develop the preconcentration and sample preparation method, based on two liquid phase microextraction procedure prior to UV-Vis spectrophotometer. The target compounds including diclofenac and ibuprofen were extracted from an aqueous sample solution (donor phase) into an organic solvent (acceptor phase). In this method, contrary to the ordinary single drop liquid-phase microextraction technique, a large drop of an organic solvent is freely suspended at the bottom of the vortex of the aqueous sample solution which is being agitated by a stirring bar, without using a microsyring as supporting device. The organic solvents which are used in this work should be insoluble or have very low solubility in water. After an optimal extraction time, a portion of the organic drop was withdrawn back into a 500 μL HPLC microsyringe and then inserted into a quartz microcell. For reducing the volume of the organic acceptor phase, the internal volume of this microcell is decreased by adding of about 100 μL of water which is placed in the bottom of the cell where is not in the optical path. Several important parameters which in?uenced the extraction efficiency such as the kind of extracting solvent, volume of the organic acceptor phase, extraction time, stirring rate, pH of the donor phase and salt effect were investigated. Under the optimal conditions by plotting peak areas versus concentrations of the analytes in the sample solution, calibration curves were obtained. The precision of the method (RSD%), limit of detections (LODs) and other figures of merit werer calculated. The modified procedurer was used for the extraction and recovery of the analytes from real water samples such as tap and mineral waters. All experiments were carried out at the room temperature, (22 ± 0.5 °C).

Keywords