title: Enhanced stability of blood matrices using a dried sample spot assay to measure human butyrylcholinesterase activity and nerve agent adducts.
abstract: Dried matrix spots are safer to handle and easier to store than wet blood products, but factors such as intraspot variability and unknown sample volumes have limited their appeal as a sampling format for quantitative analyses. In this work, we introduce a dried spot activity assay for quantifying butyrylcholinesterase (BChE) specific activity which is BChE activity normalized to the total protein content in a sample spot. The method was demonstrated with blood, serum, and plasma spotted on specimen collection devices (cards) which were extracted to measure total protein and BChE activity using a modified Ellman assay. Activity recovered from dried spots was ∼80% of the initial spotted activity for blood and >90% for plasma and serum. Measuring total protein in the sample and calculating specific activity substantially improved quantification and reduced intraspot variability. Analyte stability of nerve agent adducts was also evaluated, and the results obtained via BChE-specific activity measurements were confirmed by quantification of BChE adducts using a previously established LC-MS/MS method. The spotted samples were up to 10 times more resistant to degradation compared to unspotted control samples when measuring BChE inhibition by the nerve agents sarin and VX. Using this method, both BChE activity and adducts can be accurately measured from a dried sample spot. This use of a dried sample spot with normalization to total protein is robust, demonstrates decreased intraspot variability without the need to control for initial sample volume, and enhances analyte stability.
authors.affiliation: †Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway NE, Atlanta, Georgia 30341, United States.
authors.forename: Jonas W
authors.initials: JW
authors.lastname: Perez
authors.affiliation: †Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway NE, Atlanta, Georgia 30341, United States.
authors.forename: Brooke G
authors.initials: BG
authors.lastname: Pantazides
authors.affiliation: ‡Oak Ridge Institute for Science and Education Fellowship at the Center for Disease Control and Prevention, Atlanta, Georgia 30341, United States.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Watson
authors.affiliation: †Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway NE, Atlanta, Georgia 30341, United States.
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Thomas
authors.affiliation: †Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway NE, Atlanta, Georgia 30341, United States.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Blake
authors.affiliation: †Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway NE, Atlanta, Georgia 30341, United States.
authors.forename: Rudolph C
authors.initials: RC
authors.lastname: Johnson
mesh_terms: D002091:Butyrylcholinesterase / Q000032:analysis* / Q000378:metabolism; D002619:Chemical Warfare Agents / Q000032:analysis; D059788:Dried Blood Spot Testing / Q000379:methods*; D006801:Humans; D000067397:Nerve Agents / Q000032:analysis*; D013048:Specimen Handling
chemical_list: D002619:Chemical Warfare Agents; D000067397:Nerve Agents; D002091:Butyrylcholinesterase