title: Dispersive liquid-liquid microextraction based on solidification of floating organic drop and high-performance liquid chromatography to the analysis of cocaine's major adulterants in human urine.
abstract: A simple method has been proposed for the determination of cocaine's major adulterants (caffeine, levamisole, lidocaine, phenacetin, diltiazem, and hydroxyzine) in human urine by dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) in combination with high-performance liquid chromatography - photodiode array detector (HPLC-PDA). The reversed-phase chromatographic separation was obtained with a column C18 extended (250×4.6mm; 5μm; 80Å) in gradient elution mode using acetonitrile-trifluoroacetic acid 0.026% (v,v) (pH=2.5) at 1mLmin-1as mobile phase, at 25°C, and detection at 235nm. The analysis time was 25min. This condition had the best resolution factors (>1.15), retention factors (>0.68), number of plates (>2094.9), and separation factors (>1.05) for all targets, indicating a good separation. The kind of extraction and dispersive solvent were investigated for unifactorial design. The buffer pH, the volume of extraction and disperser solvent, and the amount of salt were optimized for full factorial design. Under optimum conditions, human urine samples were alkalized with 0.5M sodium phosphate buffer (pH 10) and added to sodium chloride (20%m/v). Acetonitrile (150μL) and 1-dodecanol (30μL) were used as dispersive and extraction solvent, respectively. The method presented linear range of 312.5-3125ngmL-1to caffeine and levamisole and 187.5-1875ngmL-1to lidocaine, phenacetin, diltiazem, and hydroxyzine. The limit of quantification was 187.5ngmL-1to lidocaine, phenacetin, diltiazem, and hydroxyzine and 312.5ngmL-1for caffeine and levamisole. The recovery mean values were between 6.0 and 42.6%. The method showed good precision and accuracy, with within- and between-run relative standard deviation and relative error less than 15%. The samples were stable after freeze-thaw cycle and short-term room temperature stability tests. Besides, this method was satisfactorily applied in urine of cocaine users. It is expected that this method, which was the first to combine the use of DLLME-SFO and HPLC-PDA for the determination of cocaine's major adulterants in human urine, will contribute to the accuracy in the diagnosis of acute intoxication, the proper planning of therapeutic measures, as well as to the favorable prognostic of cocaine intoxicated patients.
authors.affiliation: Federal University of Sergipe, Pharmacy Departament, Avenida Marechal Rondon, S/n; Jardim Rosa Elze, São Cristóvão, Sergipe, 49100-000, Brazil.
authors.forename: Laís Cristina Santana
authors.initials: LC
authors.lastname: Sena
authors.affiliation: Federal University of Sergipe, Physiology Departament, Avenida Marechal Rondon, S/n; Jardim Rosa Elze, São Cristóvão, Sergipe, 49100-000, Brazil.
authors.forename: Humberto Reis
authors.initials: HR
authors.lastname: Matos
authors.affiliation: Federal University of Sergipe, Chemistry Departament, Avenida Marechal Rondon, S/n; Jardim Rosa Elze, São Cristóvão, Sergipe, 49100-000, Brazil.
authors.forename: Haroldo Silveira
authors.initials: HS
authors.lastname: Dórea
authors.affiliation: Federal University of Pernambuco, Departament of Chemical Engineering, Rua Prof. Artur de Sá, s/n; Cidade Universitária, Recife, Pernambuco, 50740-521, Brazil.
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: Pimentel
authors.affiliation: Federal University of Pernambuco, Pharmaceutical Science Departament, Rua Prof. Artur de Sá, s/n; Cidade Universitária, Recife, Pernambuco, 50740-521, Brazil.
authors.forename: Danielle Cristine Almeida Silva
authors.initials: DC
authors.lastname: de Santana
authors.affiliation: Federal University of Pernambuco, Pharmaceutical Science Departament, Rua Prof. Artur de Sá, s/n; Cidade Universitária, Recife, Pernambuco, 50740-521, Brazil. Electronic address: fmalagueno@hotmail.com.
authors.forename: Fernando José Malagueño
authors.initials: FJ
authors.lastname: de Santana
mesh_terms: D000328:Adult; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003042:Cocaine / Q000302:isolation & purification* / Q000652:urine*; D004340:Drug Contamination; D005260:Female; D006801:Humans; D059627:Liquid Phase Microextraction / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D003042:Cocaine
keywords: Dispersive liquid-liquid microextraction based on solidification of floating organic drop; Drug adulteration; Liquid chromatography; Street cocaine; Urine toxicology analysis