title: Development of quantitative method for determination of γ-glutamyl peptides by capillary electrophoresis tandem mass spectrometry: an efficient approach avoiding matrix effect.
abstract: Serum γ-glutamyl di- and tripeptides have proven to be useful biomarkers to accurately predict nine different forms of liver disease. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with multiple reaction monitoring (MRM), serum and liver samples spiked with γ-glutamyl peptide standards were analyzed to estimate accuracy. Unexpectedly, the recovery rates for several γ-glutamyl peptides in the serum samples were quite low, whereas values for some γ-glutamyl peptides in the liver samples were highly elevated. Most of these peptides were barely retained on the reverse-phase column, resulting in significant ion suppression or enhancement. In contrast, a capillary electrophoresis tandem mass spectrometry (CE-MS/MS) method with MRM was minimally affected by matrix effects. Of the 39 tested compounds, most of γ-glutamyl peptides that did not contain a thiol substituent in its structure gave acceptable recoveries (70-120%), and limits of detection for the analytes were between 3.6 and 800 nmol/l with pressure injection at 5 kPa for 10 s (ca. 10 nl). The CE-MS/MS method provided high resolution and proved to be highly selective and sensitive, its utility being demonstrated by the determination of γ-glutamyl di- and tripeptides in serum and liver samples.
authors.affiliation: Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Kakuganji, Tsuruoka, Yamagata 997-0052, Japan. Electronic address: hirayama@ttck.keio.ac.jp.
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Hirayama
authors.affiliation: Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Kakuganji, Tsuruoka, Yamagata 997-0052, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Igarashi
authors.affiliation: Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Kakuganji, Tsuruoka, Yamagata 997-0052, Japan. Electronic address: mt@sfc.keio.ac.jp.
authors.forename: Masaru
authors.initials: M
authors.lastname: Tomita
authors.affiliation: Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Kakuganji, Tsuruoka, Yamagata 997-0052, Japan. Electronic address: soga@sfc.keio.ac.jp.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Soga
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods; D019075:Electrophoresis, Capillary / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000737:chemistry; D010455:Peptides / Q000032:analysis*; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D010455:Peptides
keywords: Capillary electrophoresis tandem mass spectrometry (CE-MS/MS); Liquid chromatography–tandem mass spectrometry (LC–MS/MS); Liver disease; Matrix effect; γ-Glutamyl peptides