Functionalized carbon nanotube/ionic liquid-coated wire as a new fiber assembly for determination of methamphetamine and ephedrine by gas chromatography-mass spectrometry

Abstract

A new ionic liquid (IL), 1-methyl 3-[(3-octylamino)propyl] imidazolium bis(trifluoromethane sulphonyl)imide [OAPMIM][NTf₂], was synthesized and characterized by ¹H-NMR. The multi-walled carbon nanotubes were functionalized with diethyl amine (FMWCNT) and dispersed in this ionic liquid. Then gel-like solution, once formed, was immobilized on a stainless steel wire to act as a novel solid phase microextraction fiber. This fiber was applied for the purpose of extraction/preconcentration of methamphetamine (MAP) and ephedrine (EP) prior to determination by gas chromatography-mass spectrometry. The efficiency of fiber coating in the extraction of methamphetamine and ephedrine was compared with that of 1-octyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide [OMIM][NTf₂] and N-octylpyrdinuim hexaflourophosphate [OPY][PF₆] and, non-functionalized multi-wall carbon nanotubes have/had different polarities and physical properties. The highest efficiency and most desirable results were achieved using [OAPMIM][NTf₂]-FMWCNT as fiber coating. The calibration curves were linear in the ranges of 1 to 150 and 0.5 to 250 μg L⁻¹ for MAP and EP, respectively. The limits of detection (LODs) were obtained as 0.1 and 0.07 μg L⁻¹ for MAP and EP, respectively. The developed method was successfully applied to the determination of MAP and EP in urine samples, and the recoveries were found to be 99.0(±5.0)% at the spiking level of 0.1 μg mL⁻¹.