title: A green method for the determination of cocaine in illicit samples.
abstract: Direct determination of cocaine in untreated seized samples has been made based on diffuse reflectance measurements of the near infrared (NIR) radiation through samples contained inside standard glass vials. The method used a series of previously analyzed samples, by the reference gas chromatography method, to build a partial least squares calibration model which was validated using an independent set of samples. The use of a general model for samples containing from 11.38% till 86.44% (w/w) cocaine was based on the use of spectral ranges from 12500.7 to 10128.6, 9339.8 to 6967.7 and 5388.3 to 4597.6cm(-1) with previous first derivative and vector normalization data pre-processing and provided a root mean square error of prediction (RMSEP) of 4.0% (w/w) with a residual prediction deviation (RPD) of 3.9% (w/w), based on the use of 8 latent variables, 34 samples for calibration and an independent set of 44 samples for validation. The aforementioned results could be improved on considering two separate models, one for high concentrated bulk samples and another for samples diluted with cutting agents. Additionally a new set of batch samples with cocaine concentrations from 60% till 84% was evaluated by using the developed method.
authors.affiliation: Laboratorio de la Inspección Farmacéutica y Control de Drogas de la Delegación de Gobierno en la Comunidad Valenciana, Área de Sanidad, Inspección de Farmacia, Muelle de la Aduana S/N, 46024 Valencia, Spain. Electronic address: clara.perez@seap.minhap.es.
authors.forename: Clara
authors.initials: C
authors.lastname: Pérez-Alfonso
authors.affiliation: Laboratorio de la Inspección Farmacéutica y Control de Drogas de la Delegación de Gobierno en la Comunidad Valenciana, Área de Sanidad, Inspección de Farmacia, Muelle de la Aduana S/N, 46024 Valencia, Spain. Electronic address: nieves.galipienso@seap.minhap.es.
authors.forename: Nieves
authors.initials: N
authors.lastname: Galipienso
authors.affiliation: Department of Analytical Chemistry, University of Valencia, Research Building "Jeroni Muñoz", Dr. Moliner Street, 46100 Burjassot (Valencia), Spain. Electronic address: salvador.garrigues@uv.es.
authors.forename: Salvador
authors.initials: S
authors.lastname: Garrigues
authors.affiliation: Department of Analytical Chemistry, University of Valencia, Research Building "Jeroni Muñoz", Dr. Moliner Street, 46100 Burjassot (Valencia), Spain. Electronic address: miguel.delaguardia@uv.es.
authors.forename: Miguel
authors.initials: M
authors.lastname: de la Guardia
mesh_terms: D003042:Cocaine / Q000737:chemistry*; D004340:Drug Contamination; D013287:Illicit Drugs / Q000737:chemistry*; D016018:Least-Squares Analysis; D009294:Narcotics / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared
chemical_list: D013287:Illicit Drugs; D009294:Narcotics; D003042:Cocaine
keywords: Cocaine; Green analytical method; Illicit samples; Near infrared; Partial least squares