title: The matrix effect in particle beam liquid chromatography/mass spectrometry and reliable quantification by isotope dilution.
abstract: The transport efficiency of the particle beam liquid chromatography/mass spectrometer interface is influenced by analyte concentration contributing to a widely reported non-linearity. In this work, coeluting, isotope-labeled internal standards were investigated as 'carriers' to improve the transport efficiency and linearity. Three styrene metabolites--mandelic, phenylglyoxylic and hippuric acids--and their pentadeutero analogs were separated by reversed-phase liquid chromatography (LC) with an ammonium acetate-acetonitrile mobile phase. Selected positive ions produced by electron ionization were monitored to generate particle beam LC/MS calibration curves. The present study demonstrates that particle beam LC/MS not only is non-linear, but also is subject to a matrix effect presumably by the same mechanism responsible for non-linearity. Coeluting, isotope-labeled internal standards were ineffective at linearizing the particle beam liquid chromatograph/mass spectrometer detector response. Isotope dilution quantification, however, compensates for variable transport efficiencies, linearizes calibration and compensates for the matrix effect, affording reliable quantification of the styrene metabolites.
authors.affiliation: Hazardous Materials Laboratory, Berkeley, California 94704.
authors.forename: F R
authors.initials: FR
authors.lastname: Brown
authors.forename: W M
authors.initials: WM
authors.lastname: Draper
mesh_terms: D000328:Adult; D002138:Calibration; D002853:Chromatography, Liquid / Q000295:instrumentation*; D006038:Glyoxylates / Q000652:urine; D006626:Hippurates / Q000652:urine; D006801:Humans; D007202:Indicators and Reagents; D008297:Male; D008333:Mandelic Acids / Q000652:urine; D013058:Mass Spectrometry / Q000295:instrumentation*; D011865:Radioisotope Dilution Technique / Q000295:instrumentation*; D020058:Styrene; D013343:Styrenes / Q000652:urine
chemical_list: D006038:Glyoxylates; D006626:Hippurates; D007202:Indicators and Reagents; D008333:Mandelic Acids; D013343:Styrenes; C012482:phenylglyoxylic acid; D020058:Styrene