title: Photo-SRM: laser-induced dissociation improves detection selectivity of Selected Reaction Monitoring mode.
abstract: Selected Reaction Monitoring (SRM) carried out on triple-quadrupole mass spectrometers coupled to liquid chromatography has been a reference method to develop quantitative analysis of small molecules in biological or environmental matrices for years and is currently emerging as a promising tool in clinical proteomic. However, sensitive assays in complex matrices are often hampered by the presence of co-eluted compounds that share redundant transitions with the target species. On-the-fly better selection of the precursor ion by high-field asymmetric waveform ion mobility spectrometry (FAIMS) or increased quadrupole resolution is one way to escape from interferences. In the present work we document the potential interest of substituting classical gas-collision activation mode by laser-induced dissociation in the visible wavelength range to improve the specificity of the fragmentation step. Optimization of the laser beam pathway across the different quadrupoles to ensure high photo-dissociation yield in Q2 without detectable fragmentation in Q1 was assessed with sucrose tagged with a push-pull chromophore. Next, the proof of concept that photo-SRM ensures more specific detection than does conventional collision-induced dissociation (CID)-based SRM was carried out with oxytocin peptide. Oxytocin was derivatized by the thiol-reactive QSY® 7 C(5)-maleimide quencher on cysteine residues to shift its absorption property into the visible range. Photo-SRM chromatograms of tagged oxytocin spiked in whole human plasma digest showed better detection specificity and sensitivity than CID, that resulted in extended calibration curve linearity. We anticipate that photo-SRM might significantly improve the limit of quantification of classical SRM-based assays targeting cysteine-containing peptides.
authors: Université Lyon, F-69622 Lyon, France.
authors: Quentin
authors: Q
authors: Enjalbert
authors: Romain
authors: R
authors: Simon
authors: Arnaud
authors: A
authors: Salvador
authors: Rodolphe
authors: R
authors: Antoine
authors: Sébastien
authors: S
authors: Redon
authors: Mehmet Menaf
authors: MM
authors: Ayhan
authors: Florence
authors: F
authors: Darbour
authors: Stéphane
authors: S
authors: Chambert
authors: Yann
authors: Y
authors: Bretonnière
authors: Philippe
authors: P
authors: Dugourd
authors: Jérôme
authors: J
authors: Lemoine
mesh_terms: D001798:Blood Proteins / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D007477:Ions / Q000032:analysis / Q000737:chemistry; D007834:Lasers; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D008958:Models, Molecular; D010121:Oxytocin / Q000097:blood / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry; D055668:Photochemical Processes; D012680:Sensitivity and Specificity; D013395:Sucrose / Q000737:chemistry; D014357:Trypsin / Q000737:chemistry
chemical_list: D001798:Blood Proteins; D007477:Ions; D010446:Peptide Fragments; D010121:Oxytocin; D013395:Sucrose; D014357:Trypsin