title: Evaluation of the influence of protein precipitation prior to on-line SPE-LC-API/MS procedures using multivariate data analysis.
abstract: Matrix effects on mass spectrometry (MS) response were investigated with three atmospheric pressure ionization (API) sources after on-line solid-phase extraction (SPE) of human plasma. On-line SPE was evaluated with one restricted access material (RAM), two large particle supports (LPS) and one monolith. A sample protein precipitation (PP) with acetonitrile (2:1) and a direct injection were tested. Principal component analysis (PCA) was performed to simplify data presentation and interpretation. Protein precipitation was found to be mandatory for reducing signal modification. Regarding sensitivity towards matrix effects after PP, atmospheric pressure photoionization (APPI) was globally the least sensitive ionization mode while electrospray ionization ESI was the most sensitive.
authors.affiliation: Laboratory of Analytical Pharmaceutical Chemistry, School of Pharmaceutical sciences, University of Geneva, University of Lausanne, Bd d'Yvoy 20, 1211 Geneva 4, Switzerland.
authors.forename: Ivano
authors.initials: I
authors.lastname: Marchi
authors.forename: Serge
authors.initials: S
authors.lastname: Rudaz
authors.forename: Maurice
authors.initials: M
authors.lastname: Selman
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Veuthey
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives; D001798:Blood Proteins / Q000302:isolation & purification*; D011232:Chemical Precipitation; D002762:Cholecalciferol; D002853:Chromatography, Liquid / Q000379:methods*; D005445:Flunitrazepam; D005473:Fluoxetine / Q000031:analogs & derivatives; D013058:Mass Spectrometry / Q000379:methods*; D008691:Methadone; D015999:Multivariate Analysis; D009862:Online Systems; D011759:Pyrrolidines; D052616:Solid Phase Extraction / Q000379:methods
chemical_list: D001798:Blood Proteins; D011759:Pyrrolidines; D005473:Fluoxetine; C028175:metalaxyl; D002762:Cholecalciferol; D005445:Flunitrazepam; C036139:norfluoxetine; D000409:Alanine; D008691:Methadone; C010724:2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine