title: Atmospheric Pressure Ionization Using a High Voltage Target Compared to Electrospray Ionization.
abstract: A new atmospheric pressure ionization (API) source, viz. UniSpray, was evaluated for mass spectrometry (MS) analysis of pharmaceutical compounds by head-to-head comparison with electrospray ionization (ESI) on the same high-resolution MS system. The atmospheric pressure ionization source is composed of a grounded nebulizer spraying onto a high voltage, cylindrical stainless steel target. Molecules are ionized in a similar fashion to electrospray ionization, predominantly producing protonated or deprotonated species. Adduct formation (e.g., proton and sodium adducts) and in-source fragmentation is shown to be almost identical between the two sources. The performance of the new API source was compared with electrospray by infusion of a mix of 22 pharmaceutical compounds with a wide variety of functional groups and physico-chemical properties (molecular weight, logP, and pKa) in more than 100 different conditions (mobile phase strength, solvents, pH, and flow rate). The new API source shows an intensity gain of a factor 2.2 compared with ESI considering all conditions on all compounds tested. Finally, some hypotheses on the ionization mechanism, similarities, and differences with ESI, are discussed. Graphical Abstract ᅟ.
authors.affiliation: Discovery Sciences, Janssen Research and Development, Turnhoutseweg 30, B-2340, Beerse, Belgium.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Lubin
authors.affiliation: Waters Corporation, Wilmslow, UK.
authors.forename: Steve
authors.initials: S
authors.lastname: Bajic
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Deirdre
authors.initials: D
authors.lastname: Cabooter
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Augustijns
authors.affiliation: Discovery Sciences, Janssen Research and Development, Turnhoutseweg 30, B-2340, Beerse, Belgium. FCUYCKEN@its.jnj.com.
authors.forename: Filip
authors.initials: F
authors.lastname: Cuyckens
keywords: API; ESI; Electrospray; Ionization; MS; Mass spectrometry; Source; UniSpray