title: HPLC/APCI mass spectrometry of saturated and unsaturated hydrocarbons by using hydrocarbon solvents as the APCI reagent and HPLC mobile phase.
abstract: Saturated and unsaturated, linear, branched, and cyclic hydrocarbons, as well as polyaromatic and heteroaromatic hydrocarbons, were successfully ionized by atmospheric pressure chemical ionization (APCI) using small hydrocarbons as reagents in a linear quadrupole ion trap (LQIT) mass spectrometer. Pentane was proved to be the best reagent among the hydrocarbon reagents studied. This ionization method generated different types of abundant ions (i.e., [M + H](+), M(+•), [M - H](+) and [M - 2H](+ •)), with little or no fragmentation. The radical cations can be differentiated from the even-electron ions by using dimethyl disulfide, thus facilitating molecular weight (MW) determination. While some steroids and lignin monomer model compounds, such as androsterone and 4-hydroxy-3-methoxybenzaldehyde, also formed abundant M(+•) and [M + H](+) ions, this was not true for all of them. Analysis of two known mixtures as well as a base oil sample demonstrated that each component of the known mixtures could be observed and that a correct MW distribution was obtained for the base oil. The feasibility of using this ionization method on the chromatographic time scale was demonstrated by using high-performance liquid chromatography (HPLC) with hexane as the mobile phase (and APCI reagent) to separate an artificial mixture prior to mass spectrometric analysis.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Jinshan
authors.initials: J
authors.lastname: Gao
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Owen
authors.forename: David J
authors.initials: DJ
authors.lastname: Borton
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Jin
authors.forename: Hilkka I
authors.initials: HI
authors.lastname: Kenttämaa
mesh_terms: D002412:Cations / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006838:Hydrocarbons / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D002412:Cations; D006838:Hydrocarbons; D012997:Solvents