Microwave assisted extraction of drugs of abuse from human urine

Green bioanalysis: an innovative and eco-friendly approach for analyzing drugs in biological matrices

Green bioanalytical techniques aim to reduce or eliminate the hazardous waste produced by bioanalytical technologies. A well-organized and practical approach towards bioanalytical method development has an enormous contribution to the green analysis. The selection of the appropriate sample extraction process, organic mobile phase components and separation technique makes the bioanalytical method green. UHPLC-MS is the best option, whereas supercritical fluid chromatography is one of the most effective green bioanalytical procedures. Nevertheless, there remains excellent scope for further research on green bioanalytical methods. This review details the various sample preparation techniques that follow green analytical chemistry principles. Furthermore, it presents green solvents as a replacement for conventional organic solvents and highlights the strategies to convert modern analytical techniques to green methods.

A straightforward and semiautomated membrane-based method as efficient tool for the determination of cocaine and its metabolites in urine samples using liquid chromatography coupled to quadrupole time-of-flight-mass spectrometry

In this study, a novel and straightforward analytical methodology was proposed for the determination of cocaine (COC) and its main metabolites benzoylecgonine (BZE) cocaethylene (CE) and hydroxy‑cocaine (COCOH) in urine samples. This approach consisted of a high-throughput and semiautomated configuration based on hollow-fiber renewal liquid membrane extraction (HFRLM) coupled to a 96-well plate system, which was proposed for the first time to analyze complex biological samples such as urine. The analytical determinations were performed using ultra-high performance liquid chromatography coupled to quadrupole time-of-flight-mass spectrometry (LC-ESI-QTOF-MS). The analytical methodology was fully optimized through Doehlert and simplex-centroid designs, and univariate approaches. Polypropylene membranes of 1 cm length were inserted in the pins of an extraction blade combined with a 96-well plate system and its pores were filled with hexane:dichloromethane:ethyl acetate (1:1:1 v/v/v) for 180 s; moreover, 20 µL of this mixture was added to the sample to allow for a renewable liquid membrane. The extraction step was carried out by keeping the blades immersed in vials containing 1.5 mL of diluted urine adjusted at pH 10 with 10% (w/v) of Na₂CO₃ during 20 min, followed by liquid desorption with 100 µL of acetonitrile_. Finally, the extract was dried under N₂ stream and resuspended with 20 µL of ultrapure water. Satisfactory analytical performance was obtained with coefficients of determination ranging from 0.9875 for BZE to 0.9986 for CE; intra-day precision ranged from 1.6 to 13.5%, and inter-day precision varied from 2.2 to 17.5%. Limits of detection ranged from 1.5 to 15.1 ng mL^-1, and limits of quantification varied from 5 to 50 ng mL^-1, with relative recoveries varied from 70.7 to 124.1%.

Rapid analysis of cocaine and metabolites in urine using microextraction in packed sorbent and GC/MS

Cocaine is still one of the most abused drugs worldwide and, as such, it is often screened for in driving-under-the-influence or workplace drug - testing scenarios. A large number of samples have usually to be processed in those situations, and this requires fast and simple extraction procedures for the detection and quantification of the drugs. The present work describes an ultrafast and fully validated procedure for the simultaneous detection and quantification of cocaine and its two main metabolites, ecgonine methyl ester and benzoylecgonine, in urine using microextraction by packed sorbent and GC-MS. A small sample volume (200 μL) was used, and a fast extraction procedure together with a microwave-assisted derivatization (800 W, 2 min) allowed the quantification of all analytes in a range of 25 to 1000 ng/mL (r ² > 0.99). Inter-day precision revealed coefficients of variation (CVs) lower than 10% for all analytes at the tested concentration levels, with an accuracy within a ±7% interval, with the exception of EME's lowest calibrator (±17%). Intra-day CVs were lower than 15% at the studied concentration levels, with a mean relative error within a ±13% interval. Recoveries ranged from 14.5 to 37.2% (EME), 67.0 to 83.3% (cocaine), and 24.6 to 43.5% (BEG), allowing the limits of detection and quantification to be set at 25 ng/mL for all compounds. Graphical Abstract Schematized analysis of cocaine and metabolites in urine by MEPS- GC/MS.

A novel test using dried blood spots for the chromatographic assay of methadone

A novel test has been developed for the analysis of methadone in dried blood spot specimens from patients undergoing methadone maintenance treatment. An isocratic reversed-phase high-performance liquid chromatography method with coulometric detection has been optimized for the determination of methadone. The clean-up of dried blood spots was performed by means of an original microextraction by packed sorbent procedure after microwave-assisted extraction of the drug with a suitable solvent. Extraction yields were satisfactory, always being higher than 90.0 %. The calibration curve was linear over the 4-500 ng mL(-1) concentration range. The method had satisfactory sensitivity (limit of quantitation of 4 ng mL(-1)), precision (relative standard deviation less than 5.8 %), selectivity and accuracy (recovery greater than 87.0 %). It was successfully applied to dried blood spot samples collected from heroin-addicted patients undergoing methadone maintenance therapy at dosages between 40 and 240 mg day(-1). The statistical analysis (Bland-Altman plot) showed that the results were in good agreement with those found from the analysis of plasma samples obtained from the same patients. Thus, the method has proved to be suitable for the monitoring of methadone by means of dried blood spots.

Novel strategies for sample preparation in forensic toxicology

This paper provides a review of novel strategies for sample preparation in forensic toxicology. The review initially outlines the principle of each technique, followed by sections addressing each class of abused drugs separately. The novel strategies currently reviewed focus on the preparation of various biological samples for the subsequent determination of opiates, benzodiazepines, amphetamines, cocaine, hallucinogens, tricyclic antidepressants, antipsychotics and cannabinoids. According to our experience, these analytes are the most frequently responsible for intoxications in Greece. The applications of techniques such as disposable pipette extraction, microextraction by packed sorbent, matrix solid-phase dispersion, solid-phase microextraction, polymer monolith microextraction, stir bar sorptive extraction and others, which are rapidly gaining acceptance in the field of toxicology, are currently reviewed.

Bioanalytical methods for the determination of cocaine and metabolites in human biological samples

Determination of cocaine and its metabolites in biological specimens is of great importance, not only in clinical and forensic toxicology, but also in workplace drug testing. These compounds are normally screened for using sensitive immunological methods. However, screening methods are unspecific and, therefore, the posterior confirmation of presumably positive samples by a specific technique is mandatory. Although GC-MS-based techniques are still the most commonly used for confirmation purposes of cocaine and its metabolites in biological specimens, the advent of LC-MS and LC-MS/MS has enabled the detection of even lower amounts of these drugs, which assumes particular importance when sample volume available is small, as frequently occurs with oral fluid. This paper will review recently-published papers that describe procedures for detection of cocaine and metabolites, not only in the most commonly used specimens, such as blood and urine, but also in other 'alternative' matrices (e.g., oral fluid and hair) with a special focus on sample preparation and chromatographic analysis.

Microwave-assisted hydrolysis and extraction of tricyclic antidepressants from human hair

The objective of this research was to develop, optimize, and validate a modern, rapid method of preparation of human hair samples, using microwave irradiation, for analysis of eight tricyclic antidepressants (TCADs): nordoxepin, nortriptyline, imipramine, amitriptyline, doxepin, desipramine, clomipramine, and norclomipramine. It was based on simultaneous alkaline hair microwave-assisted hydrolysis and microwave-assisted extraction (MAH–MAE). Extracts were analyzed by high-performance liquid chromatography with diode-array detection (HPLC–DAD). A mixture of n-hexane and isoamyl alcohol (99:1, v/v) was used as extraction solvent and the process was performed at 60°C. Application of 1.0 mol L⁻¹ NaOH and microwave irradiation for 40 min were found to be optimum for hair samples. Limits of detection ranged from 0.3 to 1.2 μg g⁻¹ and LOQ from 0.9 to 4.0 μg g⁻¹ for the different drugs. This enabled us to quantify them in hair samples within average therapeutic concentration ranges.