Pharmaceutical Science Department, Federal University of Pernambuco, Prof. Artur de Sá S/N; Cidade Universitária, Recife, PE, 50740-521, Brazil.
Laboratory of Forensic Toxicology, Criminalistics Institute, Secretary of Social Defense of Pernambuco, Marquês de Pombal 455, Santo Antônio, Recife, PE, 50100-170, Brazil.
Anal Bioanal Chem. 2019 Jun;411(16):3447-3461. doi: 10.1007/s00216-019-01797-z. Epub 2019 May 23.
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 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 (r ≥ 0.99) was obtained in the range of 180-1500 ng mL with suitable selectivity, quantification limit (180 ng mL), 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.
本研究旨在通过分散液液微萃取（DLLME）和高效液相色谱法同时测定人尿中五种主要街头可卡因掺杂物（咖啡因、利多卡因、非那西汀、地尔硫卓和羟嗪）。采用甲醇：水加三氟乙酸 0.15%（v/v）（pH = 1.9）作为流动相，在梯度洗脱模式下进行色谱分离，流速为 1 mL/min，在 25°C 下检测，检测波长为 235nm，分析时间为 20min。采用多因素实验设计方法探讨了主要 DLLME 操作参数对萃取效率的影响。最佳萃取条件为 4 mL 人尿样，用 0.5 M 磷酸钠缓冲液（pH 12）碱化，NaCl（15%，m/v），300μL 乙腈（分散溶剂）和 800μL 氯仿（萃取溶剂）。在 180-1500ng/mL 范围内得到了合适的线性响应（r≥0.99），具有良好的选择性、定量限（180ng/mL）、平均回收率（33.43-76.63%），且日内和日间测定的相对标准偏差和误差（≤15%）。经过冻融循环和短期室温稳定性试验后，分析物稳定。该方法已成功应用于可卡因使用者的实际样本，表明本研究可能有助于对可卡因依赖或可卡因急性中毒病例的适当治疗。
