Improved LC-MS Detection of Opioids, Amphetamines, and Psychedelics Using TrEnDi.

A chemical derivatization technique called trimethylation enhancement using diazomethane (TrEnDi) improves the sensitivity of mass spectrometry for detecting 13 different drugs of misuse. All analytes were successfully permethylated, with 11 showing improved analytical characteristics. Sensitivity enhancements ranged from 1.2-fold to 24.2-fold for psilocybin, and most species showed increased reversed-phase chromatographic retention. Using 13C-isotopically labeled TrEnDi reagents resolved isobaric interference between three pairs of controlled substances. In an unconventional aprotic solvent system for electrospray ionization, TrEnDi-modified amphetamine was easily measured while unmodified amphetamine was not detected. Applied to morphine in real urine, TrEnDi achieved a percent recovery of 103.1% and a 2.4-fold sensitivity enhancement, demonstrating its versatility for trace analysis.

Study at a glance

Abstract

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 ranging from 1.2-fold to as high as 24.2-fold in the case of psilocybin, as well as increases in reversed-phase chromatographic retention for most species. Derivatization using 13C-isotopically labeled TrEnDi reagents were used to successfully resolve isobaric interference issues between three pairs of controlled substances. By using an unconventional aprotic solvent system for electrospray ionization, the benefit of a fixed-permanent positive charge was highlighted as TrEnDi-modified amphetamine was easily measured while unmodified was not detected. 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 the versatility and applicability of TrEnDi to pre-existing analytical workflows for trace analysis.