Effect of halide ions on secondary electrospray ionization-ion mobility spectrometry for the determination of TNT extracted by dispersive liquid-liquid microextraction

Abstract

In this study, secondary electrospray ionization source (SESI) was coupled with ion mobility spectrometer (IMS) and utilized for the determination of 2,4,6-trinitrotoluene (TNT) in water and wastewater samples. The sensitivity of SESI–IMS for TNT detection was compared with that obtained by ESI–IMS. The effect of different halide ions (as dopants) on the signal enhancement was evaluated and eventually KCl was selected as the most effective dopant. Sample preparation step for the pre-concentration of TNT was performed by dispersive liquid-liquid microextraction using an extraction solvent with the lower density than water. Methanol and toluene were selected as the disperser and extraction solvents, respectively. Some other affected parameters on the extraction efficiency; such as salt addition and sample acidity were also investigated. The linearity was obtained 4.0–175.0 μg L−1 and the limit of detection and quantification were calculated 1.0 and 4.0 μg L−1, respectively. Tap, River, and laboratory wastewater samples were selected to evaluate the method capability for determining the analyte in real matrices, and satisfactory analytical results were obtained.