Determination of cocaine adulterants in human urine by dispersive liquid-liquid microextraction and high-performance liquid chromatography.
PMID 31123783 · Analytical and bioanalytical chemistry · 2019 · DOI 10.1007/s00216-019-01797-z
Authors: Pedro Rafael da Silva; Laís Cristina Santana Sena; Rubens Pedro Lorena Silva; Danielle Cristine Almeida Silva de Santana; Fernando José Malagueño de Santana
Abstract
This study aimed to determine simultaneously five major street cocaine adulterants (caffeine, lidocaine, phenacetin, diltiazem, and hydroxyzine) in human urine by dispersive liquid-liquid microextraction (DLLME) and high-performance liquid chromatography. The chromatographic separation was obtained in gradient elution mode using methanol:water plus trifluoroacetic acid 0.15% (v/v) (pH = 1.9) at 1 mL min-1 as mobile phase, at 25 °C, detection at 235 nm, and analysis time of 20 min. The effect of major DLLME operating parameters on extraction efficiency was explored using the multifactorial experimental design approach. The optimum extraction condition was set as 4 mL human urine sample alkalized with 0.5 M sodium phosphate buffer (pH 12), NaCl (15%, m/v), 300 μL acetonitrile (dispersive solvent), and 800 μL chloroform (extraction solvent). Linear response (r2 ≥ 0.99) was obtained in the range of 180-1500 ng mL-1 with suitable selectivity, quantification limit (180 ng mL-1), mean recoveries (33.43-76.63%), and showing relative standard deviation and error (within and between-day assays) ≤15%. The analytes were stable after a freeze-thaw cycle and a short-term room temperature stability test. This method was successfully applied in real samples of cocaine users, suggesting that our study may contribute to the appropriate treatment of cocaine dependence or with the cases of cocaine acute intoxication.
Caffeine; Chromatography, High Pressure Liquid; Cocaine; Humans; Hydroxyzine; Illicit Drugs; Lidocaine; Limit of Detection; Liquid Phase Microextraction; Phenacetin; Reference Standards; Reproducibility of Results
Cite
Pedro Rafael da Silva; Laís Cristina Santana Sena; Rubens Pedro Lorena Silva; Danielle Cristine Almeida Silva de Santana; Fernando José Malagueño de Santana. Determination of cocaine adulterants in human urine by dispersive liquid-liquid microextraction and high-performance liquid chromatography. Analytical and bioanalytical chemistry (2019). PMID 31123783. DOI 10.1007/s00216-019-01797-z.