Design and construction of an injection port for coupling stir-bar sorptive extraction with ion mobility spectrometry

An appropriate injection port was designed and constructed for direct analysis of stir-bar sorptive extractions using an ion mobility spectrometry (IMS). The novel design of the port offers great simplicity in use, high sensitivity, and high thermal and mechanical stability. The sol-gel technique was applied to prepare polydimethylsiloxane absorbent on a stir-bar. The parameters affecting extraction efficiency including stirring rate, extraction temperature, extraction time, salt addition and desorption temperature were optimized. The detection limit of the method was calculated to be 1.5μgL^-1, for diazinon, an organophosphorus pesticide selected as a test compound. The linear dynamic range was obtained to be 5.0-200.0μgL^-1 with a determination coefficient of 0.9991 for the test compound. The intra- and inter-day relative standard deviations were calculated to be 4% and 5%, respectively. Agricultural wastewater, well water, and apple were selected as real samples. The detection limit was calculated to be 1.5μgL^-1 and 7.5μgkg^-1 for the real water samples and the apple sample, respectively. The recovery values (%) were 105 ± 6, 107 ± 3 and 96 ± 6 for the spiked agricultural wastewater, well water and apple samples, respectively. The results revealed that the injection port can be used for direct analysis of samples extracted by any sorbent support, without any further sample preparation.