Development of Magnetic Carbon Nanotubes Facilitated Dispersive-Micro Solid Phase Extraction (Mag-CNT/d-µSPE) for Forensic Applications

In the past decade, magnetic carbon nanotubes (Mag-CNTs) facilitated dispersive-micro solid phase extraction (d-µSPE) (Mag-CNTs/d-µSPE) methods have been applied in a wide range of analytes. Despite the successful applications of Mag-CNTs/d-µSPE in other fields, limited research was invested in the development and application of Mag-CNTs/d-µSPE in forensic toxicology analysis. The goal of this work was to explore the properties of two in-house synthesized Mag-CNTs and to develop Mag-CNTs/d-µSPE methods for forensic applications. Two surface functionalized Mag-CNTs: carboxyl Mag-CNTs (Mag-CNTs-COOH) and sulfonyl Mag-CNTs (Mag-CNTs-SO3H), were synthesized and characterized. Successful Mag-CNTs/d-µSPE were developed using both Mag-CNTs to extract a cyanide metabolite, 2-aminothiazoline-4-carboxylic acid (ATCA) from biological matrices coupled with gas chromatography-mass spectrometry (GC-MS) analysis. Sensitivity of the Mag-CNTs-COOH/d-µSPE was enhanced using a one-step desorption/derivatization approach. The methods of both Mag-CNTs were validated according to the ANSI/ASB guidelines and their performances were compared to a SPE method. The successful results hopefully will accelerate the adoptability of ATCA analysis in routine cyanide analysis in crime laboratories. Other target analytes focused in this work was opiates present in poppy seed tea samples. Tea brewed from “unwashed” poppy seed was used as home remedy for pain relief and was considered as “legal high.” Different recipes were suggested on online forums to prolong the euphoria and analgesic effects after tighter regulations were imposed. A Mag-CNTs-SO3H/d-µSPE workflow was developed and validated to determine the concentrations of morphine, codeine, and thebaine present in poppy seed tea samples brewed using these suggested recipes. Potential lethal opiate concentrations were obtained from some poppy seed tea samples when moderate amount suggested for new users were used. The reusability and the potential carryover issues of the Mag-CNTs were also assessed in this work. The two Mag-CNTs maintained comparable extraction efficiency through at least four regeneration cycles and demonstrated no carryover issues. The successful development, validation, and applications of the renewable Mag-CNTs/d-µSPE methods showed the strong potential as a greener and efficient alternative sample preparation method for forensic analyses.