Quantitation of ortho‐cresyl phosphate adducts to butyrylcholinesterase in human serum by immunomagnetic‐UHPLC‐MS/MS |
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| Authors: | Darryl Johnson Melissa D Carter Brian S Crow Samantha L Isenberg Leigh Ann Graham H Akin Erol Caroline M Watson Brooke G Pantazides Marcel J van der Schans Jan P Langenberg Daan Noort Thomas A Blake Jerry D Thomas Rudolph C Johnson |
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| Affiliation: | 1. Oak Ridge Institute for Science and Education, Centers for Disease Control and Prevention, Atlanta, GA, USA;2. Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA;3. The Netherlands Organization for Applied Scientific Research (TNO), Technical Sciences, CBRN Protection, Rijswijk, The Netherlands |
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| Abstract: | Tri‐ortho‐cresyl phosphate (ToCP) is an anti‐wear, flame retardant additive used in industrial lubricants, hydraulic fluids and gasoline. The neurotoxic effects of ToCP arise from the liver‐activated metabolite 2‐(o‐cresyl)‐4H‐1,3,2‐benzodioxaphosphoran‐2‐one (cresyl saligenin phosphate or CBDP), which inhibits esterase enzymes including butyrylcholinesterase (BChE). Following BChE adduction, CBDP undergoes hydrolysis to form the aged adduct ortho‐cresyl phosphoserine (oCP‐BChE), thus providing a biomarker of CBDP exposure. Previous studies have identified ToCP in aircraft cabin and cockpit air, but assessing human exposure has been hampered by the lack of a laboratory assay to confirm exposure. This work presents the development of an immunomagnetic‐UHPLC‐MS/MS method for the quantitation of unadducted BChE and the long‐term CBDP biomarker, oCP‐BChE, in human serum. The method has a reportable range from 2.0 ng/ml to 150 ng/ml, which is consistent with the sensitivity of methods used to detect organophosphorus nerve agent protein adducts. The assay demonstrated high intraday and interday accuracy (≥85%) and precision (RSD ≤ 15%) across the calibration range. The method was developed for future analyses of potential human exposure to CBDP. Analysis of human serum inhibited in vitro with CBDP demonstrated that the oCP‐BChE adduct was stable for at least 72 h at 4, 22 and 37 °C. Compared to a previously reported assay, this method requires 75% less sample volume, reduces analysis time by a factor of 20 and demonstrates a threefold improvement in sensitivity. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. |
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| Keywords: | tri‐ortho‐cresyl‐phosphate butyrylcholinesterase cresyl saligenin phosphate Jamaica ginger paralysis organophosphate‐induced delayed neuropathy |
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