Determination of phenytoin at trace levels in domestic wastewater and synthetic urine samples by gas chromatography-mass spectrometry after its preconcentration by simple liquid-phase microextraction.

This work presents a sensitive and accurate analytical method for the determination of phenytoin at trace levels in domestic wastewater and synthetic urine samples by gas chromatography-mass spectrometry (GC-MS) after the metal sieve-linked double syringe liquid-phase microextraction (MSLDS-LPME) method. A metal sieve was produced in our laboratory in order to disperse water-immiscible extraction solvents into aqueous media. Univariate optimization studies for the selection of proper extraction solvent, extraction solvent volume, mixing cycle, and initial sample volume were carried out. Under the optimum MSLDS-LPME conditions, mass-based dynamic range, limit of quantitation (LOQ), limit of detection (LOD), and percent relative standard deviation (%RSD) for the lowest concentration in calibration plot were figured out to be 100.5-10964.2 μg kg-1, 150.6 μg kg-1, 45.2 μg kg-1, and 9.4%, respectively. Detection power was improved as 187.7-folds by the developed MSLDS-LPME-GC-MS system while enhancement in calibration sensitivity was recorded as 188.0-folds. In the final step of this study, the accuracy and applicability of the proposed system were tested by matrix matching calibration strategy. Percent recovery results for domestic wastewater and synthetic urine samples were calculated as 95.6-110.3% and 91.7-106.6%, respectively. These results proved the accuracy and applicability of the proposed preconcentration method, and the obtained analytical results showed the efficiency of the lab-made metal sieve apparatus.