title: Microchip sonic spray ionization.
abstract: The first microchip version of sonic spray ionization (SSI) as an atmospheric pressure ionization source for mass spectrometry (MS) is presented. The microchip used for SSI has recently been developed in our laboratory, and it has been used before as an atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) source. Now the ionization is achieved simply by applying high (sonic) speed nebulizer gas, without heat, corona discharge, or high voltage. The microchip SSI was applied to the analysis of tetra-N-butylammonium, verapamil, testosterone, angiotensin I, and ibuprofen. The limits of detection were in the range of 15 nM to 4 microM. The technique was found to be highly dependent on the position of the chip toward the mass spectrometer inlet, and on the gas and the sample solution flow rates. The microchip SSI provided dynamic linearity following a pattern similar to that used with electrospray, good quantitative repeatability (RSD=16%), and long-term signal stability.
authors: Division of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 University of Helsinki, Finland. jaroslav.pol@helsinki.fi
authors: Jaroslav
authors: J
authors: Pól
authors: Tiina J
authors: TJ
authors: Kauppila
authors: Markus
authors: M
authors: Haapala
authors: Ville
authors: V
authors: Saarela
authors: Sami
authors: S
authors: Franssila
authors: Raimo A
authors: RA
authors: Ketola
authors: Tapio
authors: T
authors: Kotiaho
authors: Risto
authors: R
authors: Kostiainen
mesh_terms: D000803:Angiotensin I / Q000032:analysis*; D007052:Ibuprofen / Q000032:analysis*; D056656:Lab-On-A-Chip Devices; D046208:Microchip Analytical Procedures / Q000379:methods*; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013739:Testosterone / Q000032:analysis*; D013997:Time Factors; D014700:Verapamil / Q000032:analysis*
chemical_list: D000644:Quaternary Ammonium Compounds; D013739:Testosterone; D000803:Angiotensin I; D014700:Verapamil; D007052:Ibuprofen