Combination of carbon nanotube reinforced hollow fiber membrane microextraction with gas chromatography-mass spectrometry for extraction and determination of some nitroaromatic explosives in environmental water

Abstract

A novel method was demonstrated for the determination of seven nitroaromatic components in environmental water samples using a combination of carbon nanotube reinforced hollow fiber membrane microextraction with gas chromatography-mass spectrometry (GC-MS). With this methodology, functionalized multi-walled carbon nanotubes (MWCNTs) immobilized into the pore structure of a polymeric membrane were evaluated for the extraction and preconcentration of these nitroaromatic explosives. This was accomplished by circulating–flowing an aqueous dispersion of the MWCNTs through a polypropylene hollow fiber placed into an ultrasonic bath using an HPLC pump. Under ultrasonic agitation, MWCNTs were forced into and trapped within the pore structure in both sides of the polypropylene fiber. The membrane extraction used in this research is a three-phase supported liquid membrane consisting of an aqueous (donor phase), organic solvents/nano sorbent (membrane) and organic (acceptor phase) system operated in the direct immersion sampling mode. In order to obtain high efficiency of this novel technique, the main parameters were optimized. Under the optimum conditions, the method presents good level of repeatabilities (RSDs less than 5.7%). Calculated calibration curves gave good levels of linearity with correlation coefficient values of between 0.9937 and 0.9968. Limit of detections (LODs) ranged from 0.03 ng mL⁻¹ (for 2,6-dinitrotoluene) to 0.94 ng mL⁻¹ (for 2-amino-4,6-dinitrotoluene). The proposed method was subsequently used successfully for the determination of all the analytes at trace levels in samples obtained from environmental waters.