title: Surface analysis under ambient conditions using plasma-assisted desorption/ionization mass spectrometry.
abstract: A novel plasma-assisted desorption/ionization (PADI) method that can be coupled with atmospheric pressure sampling mass spectrometry to yield mass spectral information under ambient conditions of pressure and humidity from a range of surfaces without the requirement for sample preparation or additives is reported. PADI is carried out by generating a nonthermal plasma which interacts directly with the surface of the analyte. Desorption and ionization then occur at the surface, and ions are sampled by the mass spectrometer. The PADI technique is demonstrated and compared with desorption electrospray ionization (DESI) for the detection of active ingredients in a range of over-the-counter and prescription pharmaceutical formulations, including nonsterodial anti-inflammatory drugs (mefenamic acid, Ibugel, and ibuprofen), analgesics (paracetamol, Anadin Extra), and Beecham's "all in one" cold and flu remedy. PADI has also been successfully applied to the analysis of nicotine in tobacco and thiosulfates in garlic. PADI experiments have been performed using a prototype source interfaced with a Waters Platform LCZ single-quadrupole mass spectrometer with limited modifications and a Hiden Analytical HPR-60 molecular beam mass spectrometer (MBMS). The ability of PADI to rapidly detect active ingredients in pharmaceuticals without the need for prior sample preparation, solvents, or exposed high voltages demonstrates the potential of the technique for high-throughput screening in a pharmaceutical or forensic environment.
authors.affiliation: Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom.
authors.forename: Lucy V
authors.initials: LV
authors.lastname: Ratcliffe
authors.forename: Frank J M
authors.initials: FJ
authors.lastname: Rutten
authors.forename: David A
authors.initials: DA
authors.lastname: Barrett
authors.forename: Terry
authors.initials: T
authors.lastname: Whitmore
authors.forename: David
authors.initials: D
authors.lastname: Seymour
authors.forename: Claire
authors.initials: C
authors.lastname: Greenwood
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Aranda-Gonzalvo
authors.forename: Steven
authors.initials: S
authors.lastname: Robinson
authors.forename: Martin
authors.initials: M
authors.lastname: McCoustra
mesh_terms: D000700:Analgesics / Q000032:analysis; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis; D001274:Atmospheric Pressure; D005737:Garlic / Q000737:chemistry; D006813:Humidity; D009538:Nicotine / Q000032:analysis; D004364:Pharmaceutical Preparations / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013499:Surface Properties; D013885:Thiosulfates / Q000032:analysis
chemical_list: D000700:Analgesics; D000894:Anti-Inflammatory Agents, Non-Steroidal; D004364:Pharmaceutical Preparations; D013885:Thiosulfates; D009538:Nicotine