We present recent results from plasma-assisted desorption/ionisation mass spectrometry (PADI-MS). PADI-MS is a new technique that yields mass spectral information under ambient conditions of pressure and humidity from a range of surfaces without the requirement for sample preparation or additives.
Plasma assisted desorption and ionisation is achieved by directing a non-thermal plasma directly onto the surface of interest. Desorption occurs from the surface and the subsequent ionisation products are detected by a quadrupole mass spectrometer. The quadrupole mass spectrometer sampling system consists of a three stage differentially pumped Campargue type molecular beam apparatus (Hiden Analytical, Warrington, UK).
The PADI technique has been demonstrated for the detection of active ingredients in a range of over-the-counter and prescription pharmaceutical formulations, including non-sterodial anti-inflammatory drugs (mefenamic acid, ibugelTM and ibuprofen), analgesics (paracetamol, Anadin ExtraTM) and Beecham’s ‘all in one’ cold and flu remedy. The tech-nique has also been successfully applied to the analysis of nicotine in tobacco and thiosulfates in garlic as well as to fragrance compounds in solution. The ability of PADI-MS to rapidly detect active ingredients in pharmaceuticals, and from liquids, without prior sample preparation, solvents or exposed high voltages demonstrates the potential of the technique for high throughput screening in a pharmaceutical or forensics environment.
[1] Ratcliffe et. al., submitted to Anal. Chem.
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