Developing a new sensitive solid-phase microextraction fiber based on carbon nanotubes for preconcentration of morphine

Abstract

The ability of extraction and preconcentration of small amounts of substances from biological samples is important in forensic medicine. In the present study, we produced a new solid-phase microextraction fiber based on carbon nanotube (CNTs) for extraction and preconcentration of small amount of morphine in urine sample. Raw nanofibers were first carboxylated with H2SO4/HNO3 (3:1) and then functionalized with ethylenediamine. Functionalization was confirmed by FTIR and Raman spectroscopy as well as SEM analysis. The functionalized CNTs were coated on a porous polypropylene hollow fiber. A new electrical device was designed and manufactured for adsorption–desorption of the analyte, in which the voltage could be reversed and the analytes could desorb into the washing solution for HPLC analysis. The results showed that the prepared fiber could adsorb a very low concentration of morphine (0.5 ppb) in urine matrix, and was successfully used for up to 50 times with no significant loss in the extraction efficiency. Recovery of the fiber was 77% at 0.5 ppb. The optimum condition for the fiber was 2 min at 1 V of the manufactured electrical catalyst controller. This fiber can be used for the detection of a small amount of morphine in biological samples, which are not detectable by conventional methods. Simple mechanism of this fiber in preconcentrating morphine makes it a novel candidate for detection of other opiates and drugs of abuses in crime scene investigations and postmortem examinations several days after exposure. The prepared electric microextraction device could also efficiently concentrate the morphine in the urine matrix.