title: Simultaneous determination of cocaine/crack and its metabolites in oral fluid, urine and plasma by liquid chromatography-mass spectrometry and its application in drug users.
abstract: BACKGROUND
  A single LC-MS equipment was used to validate three methods for simultaneously analyzing cocaine (COC), benzoylecgonine (BZE), cocaethylene (CE), anhydroecgonine methyl ester (AEME) and anhydroecgonine (AEC) in oral fluid (OF), urine and plasma.
  
  
  METHODS
  The methods were carried out using a Kinetex HILIC column for polar compounds at 30°C. Mobile phase with isocratic condition of acetonitrile: 13mM ammonium acetate pH 6.0: methanol (55:35:10 v/v/v) at 0.8mL/min flow rate was used.
  
  
  RESULTS
  After buffer dilution (OF) and protein precipitation (urine and plasma), calibration curve ranges were 4.25-544ng/mL for oral fluid and 5-320ng/mL for urine and plasma with correlation coefficients (r) between 0.9947 and 0.9992. The lowest concentration of the calibration curves were the lower limit of quantification. No major matrix effect could be noted, demonstrating the efficiency of the cleaning procedure.
  
  
  CONCLUSIONS
  The methods were fully validated and proved to be suitable for analysis of 124 cocaine and/or crack cocaine users. Among the subjects, 56.5% reported daily use of cocaine in the previous three months. Results show a high prevalence of the analytes, with BZE as the most prevalent (94 cases), followed by COC (93 cases), AEC (70 cases), CE (33 cases) and AEME (13 cases). In addition, the concentration of BZE in urine was higher compared to OF and plasma found in the real samples, showing the facility of accumulation in chronic users in matrices with a large detection window.
authors.affiliation: Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande do Sul, Av. Ipiranga, 2752, 90610-000 Porto Alegre, RS, Brazil. Electronic address: tais.fiorentin@ufrgs.br.
authors.forename: Taís Regina
authors.initials: TR
authors.lastname: Fiorentin
authors.affiliation: Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande do Sul, Av. Ipiranga, 2752, 90610-000 Porto Alegre, RS, Brazil.
authors.forename: Felipe Bianchini
authors.initials: FB
authors.lastname: D'Avila
authors.affiliation: Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande do Sul, Av. Ipiranga, 2752, 90610-000 Porto Alegre, RS, Brazil.
authors.forename: Eloisa
authors.initials: E
authors.lastname: Comiran
authors.affiliation: Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande do Sul, Av. Ipiranga, 2752, 90610-000 Porto Alegre, RS, Brazil.
authors.forename: Amanda
authors.initials: A
authors.lastname: Zamboni
authors.affiliation: Center for Drug and Alcohol Research, Collaborating Center on Alcohol and Drugs - HCPA/SENAD, Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Rua Professor Álvaro Alvim, 400, 90420-020 Porto Alegre, RS, Brazil.
authors.forename: Juliana Nichterwitz
authors.initials: JN
authors.lastname: Scherer
authors.affiliation: Center for Drug and Alcohol Research, Collaborating Center on Alcohol and Drugs - HCPA/SENAD, Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Rua Professor Álvaro Alvim, 400, 90420-020 Porto Alegre, RS, Brazil.
authors.forename: Flavio
authors.initials: F
authors.lastname: Pechansky
authors.affiliation: Pharmaceutical Laboratory of the State of Rio Grande do Sul, State Foundation for Production and Research in Health, Av. Ipiranga, 5400, 90610-000 Porto Alegre, Brazil.
authors.forename: Paulo Eduardo Mayorga
authors.initials: PEM
authors.lastname: Borges
authors.affiliation: Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande do Sul, Av. Ipiranga, 2752, 90610-000 Porto Alegre, RS, Brazil.
authors.forename: Pedro Eduardo
authors.initials: PE
authors.lastname: Fröehlich
authors.affiliation: Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande do Sul, Av. Ipiranga, 2752, 90610-000 Porto Alegre, RS, Brazil.
authors.forename: Renata Pereira
authors.initials: RP
authors.lastname: Limberger
mesh_terms: D000293:Adolescent; D000328:Adult; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D003042:Cocaine / Q000032:analysis*; D019970:Cocaine-Related Disorders / Q000175:diagnosis*; D016578:Crack Cocaine / Q000032:analysis*; D006801:Humans; D057230:Limit of Detection; D013058:Mass Spectrometry; D012015:Reference Standards; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction; D015813:Substance Abuse Detection / Q000379:methods*; D055815:Young Adult
chemical_list: D016578:Crack Cocaine; D003042:Cocaine
keywords: Cocaine; Crack-cocaine; LC-MS; Oral fluid; Plasma; Urine