title: Desorption atmospheric pressure photoionization.
abstract: An ambient ionization technique for mass spectrometry, desorption atmospheric pressure photoionization (DAPPI), is presented, and its application to the rapid analysis of compounds of various polarities on surfaces is demonstrated. The DAPPI technique relies on a heated nebulizer microchip delivering a heated jet of vaporized solvent, e.g., toluene, and a photoionization lamp emitting 10-eV photons. The solvent jet is directed toward sample spots on a surface, causing the desorption of analytes from the surface. The photons emitted by the lamp ionize the analytes, which are then directed into the mass spectrometer. The limits of detection obtained with DAPPI were in the range of 56-670 fmol. Also, the direct analysis of pharmaceuticals from a tablet surface was successfully demonstrated. A comparison of the performance of DAPPI with that of the popular desorption electrospray ionization method was done with four standard compounds. DAPPI was shown to be equally or more sensitive especially in the case of less polar analytes.
authors.affiliation: Division of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O. Box 56, FI-00014 University of Helsinki, Finland.
authors.forename: Markus
authors.initials: M
authors.lastname: Haapala
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Pól
authors.forename: Ville
authors.initials: V
authors.lastname: Saarela
authors.forename: Ville
authors.initials: V
authors.lastname: Arvola
authors.forename: Tapio
authors.initials: T
authors.lastname: Kotiaho
authors.forename: Raimo A
authors.initials: RA
authors.lastname: Ketola
authors.forename: Sami
authors.initials: S
authors.lastname: Franssila
authors.forename: Tiina J
authors.initials: TJ
authors.lastname: Kauppila
authors.forename: Risto
authors.initials: R
authors.lastname: Kostiainen
mesh_terms: D000082:Acetaminophen / Q000737:chemistry; D000327:Adsorption; D001274:Atmospheric Pressure; D005740:Gases / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D009330:Nebulizers and Vaporizers; D010777:Photochemistry; D012680:Sensitivity and Specificity; D012997:Solvents; D013696:Temperature