title: Qualification of a surrogate matrix-based absolute quantification method for amyloid-β₄₂ in human cerebrospinal fluid using 2D UPLC-tandem mass spectrometry.
abstract: The primary aims of this work were to: 1) establish a calibrator surrogate matrix for quantification of amyloid-β (Aβ)42 in human cerebrospinal fluid (CSF) and preparation of quality control samples for LC-MS-MS methodology, 2) validate analytical performance of the assay, and 3) evaluate its diagnostic utility and compare it with the AlzBio3 immunoassay. The analytical methodology was based on a 2D-UPLC-MS-MS platform. Sample pretreatment used 5 M guanidine hydrochloride and extraction on μElution SPE columns as previously described. A column cleaning procedure involved gradual removal of aqueous solvents by acetonitrile assured consistent long-term chromatography performance. Receiver-operator characteristic (ROC) curve and correlation analyses evaluated the diagnostic utility of UPLC-MS-MS compared to AlzBio3 immunoassay for detection of Alzheimer's disease (AD). The surrogate matrix, artificial CSF containing 4 mg/mL of BSA, provides linear and reproducible calibration comparable to human pooled CSF as calibration matrix. Appropriate cleaning of the trapping and analytical columns provided every-day, trouble-free runs. Analyses of CSF Aβ42 showed that UPLC-MS-MS distinguished neuropathologically-diagnosed AD subjects from healthy controls with at least equivalent diagnostic utility to AlzBio3. Comparison of ROC curves for these two assays showed no statistically significant difference (p = 0.2229). Linear regression analysis of Aβ42 concentrations measured by this mass spectrometry-based method compared to the AlzBio3 immunoassay showed significantly higher but highly correlated results. In conclusion, the newly established surrogate matrix for 2D-UPLC-MS-MS measurement of Aβ42 provides selective, reproducible, and accurate results. The documented analytical performance and diagnostic performance for AD versus controls supports consideration as a candidate reference method.
authors.affiliation: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Korecka
authors.affiliation: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Teresa
authors.initials: T
authors.lastname: Waligorska
authors.affiliation: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Michal
authors.initials: M
authors.lastname: Figurski
authors.affiliation: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA Institute on Aging and Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Jon B
authors.initials: JB
authors.lastname: Toledo
authors.affiliation: Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Arnold
authors.affiliation: Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Murray
authors.initials: M
authors.lastname: Grossman
authors.affiliation: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA Institute on Aging and Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: John Q
authors.initials: JQ
authors.lastname: Trojanowski
authors.affiliation: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA Institute on Aging and Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Leslie M
authors.initials: LM
authors.lastname: Shaw
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid* / Q000175:diagnosis; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002138:Calibration; D002853:Chromatography, Liquid; D019791:Guanidine / Q000737:chemistry; D006801:Humans; D007118:Immunoassay; D016014:Linear Models; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid*; D011786:Quality Control; D012372:ROC Curve; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000097:Acetonitriles; D016229:Amyloid beta-Peptides; D015415:Biomarkers; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D019791:Guanidine; C032159:acetonitrile
keywords: Alzheimer's disease; amyloid-$\beta_{42}$; cerebrospinal fluid; mass spectrometry