title: Potentiometric detection in UPLC as an easy alternative to determine cocaine in biological samples.
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.
authors.affiliation: University of Antwerp, Department of Chemistry, Groenenborgerlaan 171, B-2020, Antwerp, Belgium.|University of Antwerp, Centre of Medical Genetics, Universiteitsplein 1, B-2610, Antwerp, Belgium.
authors.forename: Devin
authors.initials: D
authors.lastname: Daems
authors.affiliation: University of Antwerp, Toxicological Center, Universiteitsplein 1, B-2610, Antwerp, Belgium.
authors.forename: Alexander L N
authors.initials: AL
authors.lastname: van Nuijs
authors.affiliation: University of Antwerp, Toxicological Center, Universiteitsplein 1, B-2610, Antwerp, Belgium.
authors.forename: Adrian
authors.initials: A
authors.lastname: Covaci
authors.affiliation: University of Antwerp, Department of Chemistry, Groenenborgerlaan 171, B-2020, Antwerp, Belgium.
authors.forename: Ezat
authors.initials: E
authors.lastname: Hamidi-Asl
authors.affiliation: University of Antwerp, Centre of Medical Genetics, Universiteitsplein 1, B-2610, Antwerp, Belgium.
authors.forename: Guy
authors.initials: G
authors.lastname: Van Camp
authors.affiliation: University of Antwerp, Department of Chemistry, Groenenborgerlaan 171, B-2020, Antwerp, Belgium.
authors.forename: Luc J
authors.initials: LJ
authors.lastname: Nagels
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003042:Cocaine / Q000032:analysis*; D006801:Humans; D057230:Limit of Detection; D016014:Linear Models; D008297:Male; D011199:Potentiometry / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D003042:Cocaine
keywords: UPLC; cocaine; plasma; potentiometry; urine