title: Monitoring of the stability of cocaine and some metabolites in water and oral fluid by a newly developed CE method.
abstract: A new CE method was here developed, in order to study the stability of cocaine and some of its metabolites in water and in oral fluid. At first, standard mixtures of cocaine (COC), benzoylecgonine (BE) and cocaethylene (COET) in water were used to study the optimal CE parameters to separate the three compounds. Voltage, sample temperature and pH were investigated, and 25 kV, 25°C and a pH of 4.7 were selected to achieve the best separation. The stability of the three compounds in water and oral fluid was then monitored by applying the previously developed method. Three different storage temperatures (8, 25 and 37°C) were selected and analyses during a week were performed. A decrease of COC and COET peak areas and an increase of BE peak area were observed over time at 25 and 37°C. In addition, in oral fluid, the presence of enzymes and other proteins, and the differences in the molecular structures between COC and COET, caused a stronger degradation of the first compound. Instead, when samples were stored at a low temperature (8°C), the peak areas of the compounds did not vary. Thus, the use of this storage temperature is recommended, above all when sample must be analyzed after a relatively long time.
authors.affiliation: Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Madrid, Spain.|University Institute of Research in Police Sciences (IUICP), University of Alcalá, Madrid, Spain.
authors.forename: Valentina
authors.initials: V
authors.lastname: D'Elia
authors.affiliation: Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Madrid, Spain.
authors.forename: Matias
authors.initials: M
authors.lastname: Calcerrada
authors.affiliation: Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Madrid, Spain.|University Institute of Research in Police Sciences (IUICP), University of Alcalá, Madrid, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: Montalvo
authors.affiliation: Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Madrid, Spain.|University Institute of Research in Police Sciences (IUICP), University of Alcalá, Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: García Ruiz
mesh_terms: D001826:Body Fluids; D003042:Cocaine / Q000031:analogs & derivatives / Q000302:isolation & purification / Q000378:metabolism*; D004355:Drug Stability; D019075:Electrophoresis, Capillary / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D012463:Saliva; D013696:Temperature; D014867:Water
chemical_list: D014867:Water; C005618:benzoylecgonine; C066444:cocaethylene; D003042:Cocaine
keywords: Benzoylecgonine; Capillary electrophoresis; Cocaethylene; Cocaine stability; Oral fluid