ABSTRACT
Thin film nanofibers containing ZnTiO3 nanoparticles were used for rapid and efficient evaporation of solvents as used to extract analytes by dispersive liquid-liquid microextraction (DLLME). The method is referred to as thin film evaporation (TFE). A combination of DLLME and TFE was applied to the extraction and preconcentration of the pesticide chlorpyrifos (as a model compound) prior to analysis by ion mobility spectrometry. The ZnTiO3 nanoparticles were placed on polyacrylonitrile nanofibers which increases the porosity and surface area in the TFE process, thus causing fast and complete evaporation of solvents. The effects of sample pH value, extraction solvent and its volume, disperser solvent and volume, centrifugation time, evaporation time, and desorption temperature were optimized. The relative standard deviations of intra- and inter-day analyses were found to be 3% and 7%, respectively. The method has a linear dynamic range that covers the 0.10-3.0 µg.L-1 chlorpyrifos concentration range, the limit of detection is 0.04 µg.L-1, and the enrichment factor is up to 5400 in case of spiked samples. Some spiked field samples were analyzed and the relative recoveries ranged between 99 and 111%. When applied along with ion mobility spectrometry, the interferences caused by solvent are found to be reduced in the ionization source. This makes it possible to select a variety of solvents as needed for sample extraction. Graphical abstract Schematic presentation of dispersive liquid-liquid microextraction (DLLME) combined with thin film evaporation (TFE) for rapid vaporization of extraction solvent: Application to the pre-concentration of chlorpyrifos prior to its quantification by corona discharge-ion mobility spectrometry (CD-IMS).