Screening Method for Mononitrotoluenes in Natural Waters Using Magnetic Solvent Bar Liquid-Phase Micro-extraction Followed by Gas Chromatography-Flame Ionization Detection

A simple andefficient hollow fiber-based method,viz magnetic solvent bar liquid-phase microextraction (MSB-LPME) combined with gas chromatography-flame ionization detection (GCFID) has been successfully developed for the trace determination of mononitrotoluenes (MNTs) in natural water samples. The analytes were extracted from sample solution to the organic solvent immobilized in a fiber. Following the extraction, the analyte-adsorbed magnetic solvent bar can be easily isolated from the sample solution by a magnet which could significantlyfacilitate the operation as well asreducing the total pretreatment time. The bar was mainly eluted with acetonitrile, evaporated to dryness while the residue was dissolved in toluene and finally injected into GC-FID. At first, a series of parameters influencing microextraction performance were systematically investigated and optimized. The values of the detection limit were in the range of 0.05-0.08 μg L-1 and the RSD% for the analysis of 50.0μg L-1 of the analytes was below than 5.8% (n = 6). An acceptable linearity (0.996 ≥ r2 ≥ 0.995) and a broad linear range (0.2-200 μg L-1) were achieved. The method was eventually employed for the preconcentration and determination of the MNTs in environmental water samples and acceptable results were reached.