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Substances of misuse are becoming increasingly difficult to analyze as unique methods of smuggling are adopted and due to the rapid emergence of new psychoactive substances, increasing the pool of compounds to characterize and identify. Technologies such as gas chromatography and liquid chromatography coupled to mass spectrometry (MS) represent the gold standard for accurate and robust analysis, with on-site ambient- and portable-MS systems providing rapid methods of drug screening and testing. For many samples containing residual analyte quantities, methods to improve sensitivity through chemical derivatization are critical for accurate determination. Herein, we demonstrate for the first time the use of trimethylation enhancement using diazomethane (TrEnDi) to improve the MS-based sensitivity of 13 different drugs of misuse. All analytes were successfully permethylated, with 11 demonstrating improved analytical characteristics from TrEnDi with MS sensitivity enhancements of 1.2–24.2-fold and increases in reversed-phase chromatographic retention. Derivatization using 13C-isotopically labelled TrEnDi reagents were used to successfully resolve isobaric interference issues between three pairs of controlled substances. The sensitivity of a TrEnDi-modified analyte was increased several orders of magnitude using an unconventional aprotic solvent system for electrospray ionization. Finally, TrEnDi was employed to boost the sensitivity of morphine in a real urine matrix. Our results demonstrate a percent recovery of 103.1% and a sensitivity enhancement of 2.4-fold, demonstrating versatility and applicability of TrEnDi to pre-existing analytical workflows for trace analysis.
Rosales et al. (Wed,) studied this question.