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A Tool for Automatic Correction of Endogenous Concentrations: Application to BHB Analysis by LC–MS-MS and GC-MS


A Tool for Automatic Correction of Endogenous Concentrations: Application to BHB Analysis by LC–MS-MS and GC-MS

Desharnais, Brigitte ORCID: https://orcid.org/0000-0001-7373-656X, Lajoie, Marie-Jo, Laquerre, Julie, Savard, Stéphanie, Mireault, Pascal and Skinner, Cameron D. (2019) A Tool for Automatic Correction of Endogenous Concentrations: Application to BHB Analysis by LC–MS-MS and GC-MS. Journal of Analytical Toxicology . ISSN 0146-4760

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Official URL: https://doi.org/10.1093/jat/bkz024


Several substances relevant for forensic toxicology purposes have an endogenous presence in biological matrices: beta-hydroxybutyric acid (BHB), gamma-hydroxybutyric acid (GHB), steroids and human insulin, to name only a few. The presence of significant amounts of these endogenous substances in the biological matrix used to prepare calibration standards and quality control samples (QCs) can compromise validation steps and quantitative analyses. Several approaches to overcome this problem have been suggested, including using an analog matrix or analyte, relying entirely on standard addition analyses for these analytes, or simply ignoring the endogenous contribution provided that it is small enough. Although these approaches side-step the issue of endogenous analyte presence in spiked matrix-matched samples, they create serious problems with regards to the accuracy of the analyses or production capacity. We present here a solution that addresses head-on the problem of endogenous concentrations in matrices used for calibration standards and quality control purposes. The endogenous analyte concentration is estimated via a standard-addition type process. This estimated concentration, plus the spiked concentration are then used as the de facto analyte concentration present in the sample. These de facto concentrations are then used in data analysis software (MultiQuant, Mass Hunter, etc.) as the sample’s concentration. This yields an accurate quantification of the analyte, free from interference of the endogenous contribution. This de facto correction has been applied in a production setting on two BHB quantification methods (GC-MS and LC–MS-MS), allowing the rectification of BHB biases of up to 30 μg/mL. The additional error introduced by this correction procedure is minimal, although the exact amount will be highly method-dependent. The endogenous concentration correction process has been automated with an R script. The final procedure is therefore highly efficient, only adding four mouse clicks to the data analysis operations.

Divisions:Concordia University > Faculty of Arts and Science > Chemistry and Biochemistry
Item Type:Article
Authors:Desharnais, Brigitte and Lajoie, Marie-Jo and Laquerre, Julie and Savard, Stéphanie and Mireault, Pascal and Skinner, Cameron D.
Journal or Publication:Journal of Analytical Toxicology
Corporate Authors:Laboratoire de sciences judiciaires et de médecine légale, Department of Toxicology, 1701 Parthenais Street, Montréal, Québec, Canada H2K 3S7, Concordia University, Department of Chemistry & Biochemistry, 7141 Sherbrooke Street West, Montréal, Québec, Canada H4B 1R6
Date:29 May 2019
Digital Object Identifier (DOI):10.1093/jat/bkz024
Keywords:Endogenous, quantification, method validation, automation, BHB, RStudio
ID Code:985479
Deposited On:06 Jun 2019 18:30
Last Modified:29 May 2020 00:00
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