title: Differentiation of regioisomeric aromatic ketocarboxylic acids by positive mode atmospheric pressure chemical ionization collision-activated dissociation tandem mass spectrometry in a linear quadrupole ion trap mass spectrometer.
abstract: Positive-mode atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS(n)) was tested for the differentiation of regioisomeric aromatic ketocarboxylic acids. Each analyte forms exclusively an abundant protonated molecule upon ionization via positive-mode APCI in a commercial linear quadrupole ion trap (LQIT) mass spectrometer. Energy-resolved collision-activated dissociation (CAD) experiments carried out on the protonated analytes revealed fragmentation patterns that varied based on the location of the functional groups. Unambiguous differentiation between the regioisomers was achieved in each case by observing different fragmentation patterns, different relative abundances of ion-molecule reaction products, or different relative abundances of fragment ions formed at different collision energies. The mechanisms of some of the reactions were examined by H/D exchange reactions and molecular orbital calculations.
authors.affiliation: Department of Chemistry, Purdue University, BRWN Building, 560 Oval Dr., West Lafayette, IN 47907, USA.
authors.forename: Lucas M
authors.initials: LM
authors.lastname: Amundson
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Owen
authors.forename: Vanessa A
authors.initials: VA
authors.lastname: Gallardo
authors.forename: Steven C
authors.initials: SC
authors.lastname: Habicht
authors.forename: Mingkun
authors.initials: M
authors.lastname: Fu
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Shea
authors.forename: Allen B
authors.initials: AB
authors.lastname: Mossman
authors.forename: Hilkka I
authors.initials: HI
authors.lastname: Kenttämaa
mesh_terms: D001274:Atmospheric Pressure; D001565:Benzoates; D002264:Carboxylic Acids / Q000737:chemistry*; D005449:Fluorenes / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014867:Water
chemical_list: D001565:Benzoates; D002264:Carboxylic Acids; D005449:Fluorenes; D007659:Ketones; D014867:Water