Session: Advances in Mass Spectrometry:

Paper spray mass spectrometry (PS-MS/MS) has been shown to be a rapid, simple, and inexpensive alternative to traditional forensic drug screening methods. It can address the limitations of both immunoassays and chromatography-based techniques due to its non-reliance on sample preparation and its ability to rapidly screen for a wide array of compounds. In this study, an automated PS-MS/MS system is employed to screen for 45 commonly abused drugs and metabolites in urine. A fifty-microliter aliquot of urine is mixed with a solution containing internal standards, buffer, and recombinant beta-glucuronidase enzyme. After 15 minutes of incubation at room temperature the sample is spotted directly onto a preassembled paper spray sample cassette for analysis. The instrument operates in positive ion mode at 4kV and utilizes single reaction monitoring (SRM) to identify two transition per target compound. Due to the potential occurrence of isobaric interference, a positive result is only considered valid if primary and secondary transitions are present in a pre-established ratio. Individual urine samples are analyzed in less than two minutes and up to 240 samples can be processed per run. Six-point calibration curves covering forensically relevant concentration ranges for each analyte are used to assess the methods detection capability and linear range. Preliminary results indicate that cut-offs between 1 ng/mL and 1 ug/mL are attainable for a large drug screening assay using automated PS-MS/MS. This method may prove very useful for forensic laboratories as it allows for high through-put of complex samples without extraction, separation, and sample cleanup.

Sarah Dowling

Appearances