High-performance liquid chromatographic confirmation of cocaine and benzoylecgonine in biological samples using photodiode-array detection after toxicological screening

Confirmation of cocaine exposure by gas chromatography-mass spectrometry of urine extracts after methylation of benzoylecgonine

Volatility and thermal stability are necessary physical-chemical properties for analysing a substance by gas chromatography. A derivatization step is required before gas chromatography of benzoylecgonine (the main metabolite of cocaine). In the literature, reactions such as silylation, perfluoroalkylation or alkylation are the most frequently used to derivatize benzoylecgonine. However, they allow the formation of products sensitive to moisture or require a purification step. So, a procedure to derivatize benzoylecgonine with diazomethane before gas chromatographic analysis was evaluated. A study was performed to evaluate the efficiency of conversion of benzoylecgonine in cocaine, the necessary time for reaction and the stability of ethereal solution of diazomethane. The reaction was shown to be very fast in mild conditions and there was no need for a further purification step. When benzoylecgonine was extracted from urine by solid-phase extraction and derivatized with diazomethane, concentrations as low as 25 ng/ml could be detected using GC-MS in the full scan mode.

Determination of drugs of abuse in blood

The detection and quantitation of drugs of abuse in blood is of growing interest in forensic and clinical toxicology. With the development of highly sensitive chromatographic methods, such as high-performance liquid chromatography (HPLC) with sensitive detectors and gas chromatography-mass spectrometry (GC-MS), more and more substances can be determined in blood. This review includes methods for the determination of the most commonly occurring illicit drugs and their metabolites, which are important for the assessment of drug abuse: Methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), N-ethyl-3,4-methylenedioxyamphetamine (MDEA), 3,4-methylenedioxy-amphetamine (MDA), cannabinoids (delta-9-tetrahydrocannabinol, 11-hydroxy-delta-9-tetrahydrocannabinol, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol), cocaine, benzoylecgonine, ecgonine methyl ester, cocaethylene and the opiates (heroin, 6-monoacetylmorphine, morphine, codeine and dihydrocodeine). A number of drugs/drug metabolites that are structurally close to these substances are included in the tables. Basic information about the biosample assayed, work-up, GC column or LC column and mobile phase, detection mode, reference data and validation data of each procedure is summarized in the tables. Examples of typical applications are presented.

Quantitation of cocaine and cocaethylene in small volumes of rat whole blood using gas chromatography-mass spectrometry

A simple solid phase extraction (SPE) technique combined with gas chromatography-mass spectrometry (GC/MS) operated in selected ion monitoring (SIM) mode is described for quantitation of cocaine and cocaethylene in small samples (250 microliters) of rat whole blood. Use of (N-[2H3C])-cocaine and (N-[2H3C])-cocaethylene internal standards resulted in high sensitivity and selectivity for this analytical method. Analysis was performed using a Hewlett-Packard 5890 GC equipped with a 7673A Automatic Liquid Sampler linked to a Hewlett-Packard 5972 Mass Selective Detector. Separation of analytes was accomplished on a cross-linked methyl silicone gum capillary column (Ultra 1: 12m x 0.2mm (i.d.) x 0.33 microns). Linearity was established over a wide range of concentrations (5.0-2000.0 ng ml-1) with good precision. Limits of detection (LOD) were 1.0 and 2.0 ng ml-1 for cocaine and cocaethylene, respectively. This analytical method was designed for use in pharmacokinetic experiments studying the formation of cocaethylene following ethanol pretreatment in rats administered cocaine.

Rapid liquid-liquid extraction of cocaine from urine for gas chromatographic-mass spectrometric analysis

A novel, simple and economic liquid-liquid extraction method for isolating cocaine from urine was developed utilizing gas chromatography-mass spectrometry (GC-MS) for analysis and quantification. The use of a single nonpolar organic solvent allowed only nonpolar analytes to be extracted from the biological fluid, and consequently, no derivatization step was necessary before GC-MS analysis. Large numbers of specimens (>60) can be extracted in approximately 3 h with this procedure. The method is highly precise (C.V. <7%), accurate (>98%), sensitive (limit of detection of 5 ng/ml) and has a mean recovery of 48.8%.

Analysis of cocaine, benzoylecgonine, and cocaethylene in urine by HPLC with diode array detection

A solid phase extraction method was developed for the isolation of cocaine, benzoylecgonine, and cocaethylene from urine followed by high-performance liquid chromatography/diode array detection. The application of a new solid hybrid phase extraction technology produced much cleaner extracts than conventional extraction procedures and made the selective extraction of substances with different polarities possible. Two internal standards with great structural resemblance to benzoylecgonine (a carboxylic acid) and to the two esters, cocaine and cocaethylene, respectively, were synthesized. A linear response over a broad concentration range was obtained. The sensitivity, specificity, and accuracy were satisfactory for each analyte. Hydrolysis of cocaine and cocaethylene to benzoylecgonine during extraction and analysis was less than 0.5%. The method described can be used to corroborate cocaine use, to establish cocaine overdoses, and to study pharmacological effects of cocaine and its metabolites.

A micro liquid chromatographic assay for the determination of plasma-unbound atenolol

An improved high performance liquid chromatographic assay for plasma-unbound atenolol is described. The assay has a wide range (10-5000 ng ml-1) of linearity and a detection limit of 5 ng ml-1 (or 0.1 ng per injection) with acceptable intra- and inter-assay reproducibilities using small volumes of plasma (100 microliters). Following administration of a single dose of atenolol to the rat, nine blood samples were collected over a period of 8 h. These samples were analyzed for atenolol concentrations by a sensitive and specific microbore high performance liquid chromatograph with a photodiode-array detector. This multi-channel detector was used to acquire spectral information on atenolol and demonstrated a superior performance in comparison to all other techniques in that both qualitative and quantitative information were acquired with the system. Because of it sensitivity and applicability to plasma analysis, the assay can be used for pharmacokinetic studies and is valuable in therapeutic drug monitoring.