title: Gas chromatography-microchip atmospheric pressure chemical ionization-mass spectrometry.
abstract: An atmospheric pressure chemical ionization (APCI) microchip is presented for combining a gas chromatograph (GC) to a mass spectrometer (MS). The chip includes capillary insertion channel, stopper, vaporizer channel, nozzle and nebulizer gas inlet fabricated on the silicon wafer, and a platinum heater sputtered on a glass wafer. These two wafers are joined by anodic bonding creating a two-dimensional version of an APCI microchip. The sample from GC is directed via heated transfer line capillary to the vaporizer channel of the APCI chip. The etched nozzle forms narrow sample plume, which is ionized by an external corona discharge needle, and the ions are analyzed by a mass spectrometer. The GC-microchip APCI-MS combination provides an efficient method for qualitative and quantitative analysis. The spectra produced by microchip APCI show intensive protonated molecule and some fragmentation products as in classical chemical ionization for structure elucidation. In quantitative analysis the GC-microchip APCI-MS showed good linearity (r(2) = 0.9989) and repeatability (relative standard deviation 4.4%). The limits of detection with signal-to-noise ratio of three were between 0.5 and 2 micromol/L with MS mode using selected ion monitoring and 0.05 micromol/L with MS/MS using multiple reaction monitoring.
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O. Box 56, FIN-00014 University of Helsinki, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Ostman
authors.forename: Laura
authors.initials: L
authors.lastname: Luosujärvi
authors.forename: Markus
authors.initials: M
authors.lastname: Haapala
authors.forename: Kestas
authors.initials: K
authors.lastname: Grigoras
authors.forename: Raimo A
authors.initials: RA
authors.lastname: Ketola
authors.forename: Tapio
authors.initials: T
authors.lastname: Kotiaho
authors.forename: Sami
authors.initials: S
authors.lastname: Franssila
authors.forename: Risto
authors.initials: R
authors.lastname: Kostiainen
mesh_terms: D000840:Anisoles / Q000032:analysis; D001274:Atmospheric Pressure; D001547:Benzaldehydes / Q000032:analysis; D002849:Chromatography, Gas / Q000379:methods; D006801:Humans; D013058:Mass Spectrometry / Q000295:instrumentation* / Q000379:methods*; D009281:Naphthalenes / Q000032:analysis; D010422:Pentanones / Q000032:analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000840:Anisoles; D001547:Benzaldehydes; D009281:Naphthalenes; D010422:Pentanones; C503376:2-acetylnaphthalene; C008790:acetylacetone; C060998:anisole; C032175:benzaldehyde