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Potentiometric detection in UPLC as an easy alternative to determine cocaine in biological samples
Author(s) -
Daems Devin,
Nuijs Alexander L. N.,
Covaci Adrian,
HamidiAsl Ezat,
Van Camp Guy,
Nagels Luc J.
Publication year - 2015
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/bmc.3400
Subject(s) - chromatography , chemistry , potentiometric titration , detection limit , high performance liquid chromatography , urine , quantitative analysis (chemistry) , ion , biochemistry , organic chemistry
Abstract The analytical methods which are often used for the determination of cocaine in complex biological matrices are a prescreening immunoassay and confirmation by chromatography combined with mass spectrometry. We suggest an ultra‐high‐pressure liquid chromatography combined with a potentiometric detector, as a fast and practical method to detect and quantify cocaine in biological samples. An adsorption/desorption model was used to investigate the usefulness of the potentiometric detector to determine cocaine in complex matrices. Detection limits of 6.3 ng mL −1 were obtained in plasma and urine, which is below the maximum residue limit (MRL) of 25 ng mL −1 . A set of seven plasma samples and 10 urine samples were classified identically by both methods as exceeding the MRL or being inferior to it. The results obtained with the UPLC/potentiometric detection method were compared with the results obtained with the UPLC/MS method for samples spiked with varying cocaine concentrations. The intraclass correlation coefficient was 0.997 for serum ( n = 7) and 0.977 for urine ( n = 8). As liquid chromatography is an established technique, and as potentiometry is very simple and cost‐effective in terms of equipment, we believe that this method is potentially easy, inexpensive, fast and reliable. Copyright © 2014 John Wiley & Sons, Ltd.