Rapid orthogonal screening of forensic drugs using a compact UHPLC-PDA/SQD; a complement to GC-MS

With the recent development of hand-held and miniature mass spectrometers, low cost and compact mass detectors have become more available and accessible for on-site and routine laboratory use. Here we present a rapid ultra-high performance liquid chromatography-photodiode array/mass spectrometry (UHPLC-PDA/MS) method for the routine screening of a wide variety of illicit drugs using a small and cost effective single quadrupole MS (SQD) with electron spray ionization (ESL). Two libraries for common drugs of forensic interest, a PDA library including retention time (RT) and PDA spectra and a MS library including RT and [M+H](+)/[M-H], were developed. Using a BEH phenyl column and gradient elution of acetonitrile and 0.1% formic acid, drugs of forensic interest were detected within 8.5 min and identified based on their RT/RRT to an internal standard (Codeine-d(6)), UV spectrum, and/or MS spectrum/(de) protonated molecular mass. The method proved to be efficient, reproducible, and sensitive with a limit of detection (LOD) <= 0.5 mu g/mL for untargeted screening using PDA and MS in full scan mode and <= 0.1 mu g/mL for targeted screening by MS in select ion recording (SIR) mode. Improved isomer discrimination was achieved, when a second injection and separation by a charged column (CSH C-18) was incorporated into the same acquisition sequence. The method was applied to 20 seized drugs with similar detection limits and identifications by GC-MS. Using an orthogonal separation technique and dual detection systems, the UHPLC-PDA/SQD method serves as an attractive technique for a direct and fast screening of illicit drugs with excellent discrimination power and detection capacity. The developed method can be an alternative screening method to GC-FID and complementary technique to GC-MS for routine forensic drug screening. Published by Elsevier B.V.

Automated summary

The method presented in the study utilizes a single quadrupole mass spectrometer for rapid screening of common illicit drugs, demonstrating efficiency, reproducibility, and sensitivity. Utilizing different columns and gradient elution enabled rapid identification of drugs with low detection limits, as well as improved isomer discrimination.