Dispersive solid-phase extraction adsorbent of methamphetamine using in-situ synthesized carbon-based conductive polypyrrole nanocomposite: focus on clinical applications in human urine.

Determination of methamphetamine is of great importance in clinical and forensic laboratories because there are low dosages of drugs in the biological media and social problems created due to the methamphetamine consumption. Polymeric carbon based-nano composites are reasonable candidates for dispersive solid phase extraction method due to facial and affordable synthesis process and high selectivity and sensitivity. Nano graphene oxide polypyrolle composite was synthesized and employed as dispersive solid-phase extraction adsorbent for methamphetamine extraction from complex urine matrix. Full characterization of the prepared nano graphene oxide polypyrolle composite was completed and the influential extraction parameters were investigated through one-parameter-at-a-time method. High-performance liquid chromatography detectors were applied as detection and quantification instrument. The optimized extraction parameters included 300 µL of methanol, 10 min of extraction and desorption time, 6000 stirring rate, urine pH value of 10, 60 mg of adsorbent, and 6 mL of urine volume. After outlining the calibration curve, the linear range of the method was considered as 30-800 ng/mL. The detection limit for the suggested method was 9 ng/mL. The analysis of addicted subjects with the proposed method confirmed the utility of the method in different analytical and clinical laboratories.

An electrochemical aptasensor for methylamphetamine rapid detection by single-on mode based on competition with complementary DNA.

A simple and rapid electrochemical sensing method with high sensitivity and specificity of aptamers was developed for the detection of methylamphetamine (MAMP). A short anti-MAMP thiolated aptamer (Apt) with a methylene blue (MB) probe at 3'-end was immobilized on the surface of a gold electrode (MB-Apt-S/GE). The electrochemical signal appeared when MAMP presenting in the sample solution competed with cDNA for binding with MB-Apt-S. Under optimized conditions, the liner range of this signal-on electrochemical aptasensor for the detection of MAMP achieved from 1.0 to 10.0 nmol/L and 10.0-400 nmol/L. LOD 0.88 nmol/L were obtained. Satisfactory spiked recoveries of saliva and urine were also obtained. In this method, only 5 min were needed to incubate before the square wave voltammetry (SWV) analysis, which was much more rapid than other electrochemical sensors, leading to a bright and broad prospect for the detection of MAMP in biological sample. This method can be used for on-site rapid detection on special occasions, such as drug driving scenes, entertainment venues suspected of drug use, etc.

Enantioselective piezoelectric quartz crystal sensor for d-methamphetamine based on a molecularly imprinted polymer.

A piezoelectric quartz crystal (PQC) sensor based on a molecularly imprinted polymer (MIP) has been developed for enantioselective and quantitative analysis of d-(+)-methamphetamine (d(+)-MA). The sensor was produced by bulk polymerization and the resulting MIP was then coated on the gold electrode of an AT-cut quartz crystal. Conditions such as volume of polymer coating, curing time, type of PQC, baseline solvent, pH, and buffer type were found to affect the sensor response and were therefore optimized. The PQC-MIP gave a stable response to different concentrations of d(+)-MA standard solutions (response time = 10 to 100 s) with good repeatability (RSD = 0.03 to 3.09%; n = 3), good reproducibility (RSD = 3.55%; n = 5), and good reversibility (RSD = 0.36%; n = 3). The linear range of the sensor covered five orders of magnitude of analyte concentration, ranging from 10(-5) to 10(-1) microg mL(-1), and the limit of detection was calculated as 11.9 pg d(+)-MA mL(-1) . The sensor had a highly enantioselective response to d(+)-MA compared with its response to l(-)-MA, racemic MA, and phentermine. The developed sensor was validated by applying it to human urine samples from drug-free individuals spiked with standard d(+)-MA and from a confirmed MA user. Use of the standard addition method (SAM) and samples spiked with d(+)-MA at levels ranging from 1 x 10(-3) to 1 x 10(-2) microg mL(-1) showed recovery was good (95.3 to 110.9%).

Optoplasmonic Hybrid Materials for Trace Detection of Methamphetamine in Biological Fluids through SERS.

Optoplasmonic materials comprising both photonic and plasmonic elements are of particular interest for the development of substrates for surface-enhanced Raman spectroscopy (SERS). In this work, a layer of analyte-carrying dielectric nano/microspheres is placed on top of a monolayer of gold nanoparticles to enhance the intensity of the electric (E-) field localization and to enrich the analyte close to the electromagnetic hot spots. Numerical simulations of the hybrid structure confirm an increased and spatially expanded E-field enhancement at the interface. Due to a decreasing filling fraction with increasing size of the dielectric spheres, simulations predict a saturated SERS enhancement for dielectric microspheres with a diameter larger than 4 µm, which is confirmed by experimental SERS measurements. The dielectric microsphere can be functionalized with surface ligands that facilitate the binding of target molecules in solution. The deposition of the analyte-loaded microspheres on the self-assembled gold nanoparticle ensures a high local concentration of analytes in the electromagnetic "hot" surface. The performance of the optoplasmonic SERS approach for detecting methamphetamine in saliva and urine is tested, and the detection of analytes at nanomolar (nM) concentrations is demonstrated.

Methamphetamine disposition in oral fluid, plasma, and urine.

This review of the disposition of methamphetamine in oral fluid, plasma, and urine is based on a comprehensive controlled dosing study involving five healthy, drug-free research volunteers who resided on a closed clinical ward for 12 weeks. Subjects were administered four low (10 mg) and high (20 mg) daily oral doses of methamphetamine in two separate sessions. Near-simultaneous collections of oral fluid and plasma were performed on the first day of each low- and high-dose session. Thereafter, oral fluid was provided on each day of dosing by different oral fluid collection methods. All urine specimens were collected on an ad libitum basis throughout the study. Specimens were analyzed by gas-chromatography mass spectrometry for methamphetamine and the metabolite, amphetamine, with a limit of quantification of 2.5 ng/mL for each analyte. Methamphetamine and metabolite concentrations in oral fluid appeared to follow a similar time course in oral fluid as in plasma and were dose-proportional, but oral fluid concentrations exceeded plasma concentrations. Urine drug concentrations were substantially higher than those in oral fluid. Some drug accumulation was noted with daily dosing, but generally did not markedly influence detection times or detection rates of oral fluid tests. Detection times and detection rates for oral fluid and urine were determined at cessation of 4 days of dosing. Generally, detection times and rates for urine were longer than those observed for oral fluid at conventional cutoff concentrations. When contemplating selection of oral fluid as a test matrix, the advantages of oral fluid collection should be weighed against its shorter time of detection compared to that of urine.

Polypeptide with electroactive endgroups as sensing platform for the abused drug 'methamphetamine' by bioelectrochemical method.

Affinity-type sensors have emerged as outstanding platforms in the detection of diagnostic protein markers, nucleic acids and drugs. Thus, these novel platforms containing antibodies could be integrated into the monitoring systems for abused drugs. Herein, we established a novel detection platform for the analysis of a common illicit drug; methamphetamine (METH). Initially, a fluorescent-labeled polypeptide (EDOT-BTDA-Pala), derived from L-alanine N-carboxyanhydride (L-Ala-NCA) via ring-opening polymerization using 4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)benzo[c][1,2,5]thiadiazole-5,6-diamine (EDOT-NH2-BTDA) as initiator, was employed as a glassy carbon electrode (GCE) covering host, in order to immobilize the METH-selective antibody. Prior to the examination of analytical features, GCE/EDOT-BTDA-Pala/Antibody surface was successfully characterized in the way of electrochemical (cyclic voltammetry and electrochemical impedance spectroscopy) and microscopic techniques (scanning electron microscopy and fluorescence microscopy). As for the analytical characterization, linearity and limit of detection (LOD) were found as 10-100µg/mL with an equation of y=0.0429x-0.2347, (R2=0.996) and 13.07µg/mL, respectively. Moreover, sample application using artificial urine, saliva and serum samples spiked with METH (10, 25, 50µg/mL) were performed and LC-MS/MS system was used for further confirmation. The described platform can be adapted to monitor the other types of abused drugs by using suitably selected biorecognition elements.

Extraction of amphetamine and methamphetamine from urine specimens with Cerex Polycrom Clin II solid-phase extraction columns and the Speedisk 48 Pressure Processor.

Extraction of amphetamine and methamphetamine in urine was investigated using Cerex Polycrom Clin II solid-phase extraction columns and the Speedisk 48 Pressure Processor as a replacement for our liquid-liquid procedure. Linearity for urine standards extracted with the Cerex-Speedisk method ranged from 50 ng/mL for methamphetamine and from 150 ng/mL for amphetamine to 10,000 ng/mL for both. The mean recovery at the 500-ng/mL cutoff for three different lots of columns was 96.4% for AMP and 95.7% for MET. The mean of the within-run means for three batches was 495.4 ng/mL with a coefficient of variation (CV) of 1.2% or less for amphetamine and 496.4 ng/mL for methamphetamine with a CV of 1.7% or less. Thirty-six specimens containing amphetamine and the same number for methamphetamine were analyzed by both the Cerex-Speedisk and liquid-liquid methods. The correlation for specimens containing amphetamine gave an r2 of 0.9986 with a slope of 0.99; for methamphetamine, the r2 was 0.9997 with a slope of 0.98. The Cerex-Speedisk method cut extraction time in half, was less costly, and greatly reduced the volume of hazardous waste.

Rapid analysis of amphetamine, methamphetamine, MDA, and MDMA in urine using solid-phase microextraction, direct on-fiber derivatization, and analysis by GC-MS.

A rapid, sensitive, and solvent-free procedure for the simultaneous determination of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxymethamphetamine (MDMA) in urine was developed using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode. A headspace vial containing the urine sample, NaOH, NaCl, and amphetamine-d3 as the internal standard was heated at 100 degrees C for 20 min. A polydimethylsiloxane fiber was maintained in the vial headspace for 10 min in order to adsorb the amphetaminic compounds, which were subsequently derivatized by exposing the fiber to trifluoroacetic anhydride for 20 min in the headspace of another vial maintained at 60 degrees C for 20 min. The trifluoroacetyl derivatives were desorbed in the GC injection port for 5 min. Several parameters were considered during the method optimization process. These included a comparison of SPME with or without headspace, the required derivatization procedure, and the influence of temperature on the headspace extraction and derivatization methods. The optimized method was validated for the four compounds tested. Calibration curves showed linearity in the range 50-1000 ng/mL (r = 0.9946-0.9999). Recovery data were 71.89-103.24%. The quantitation limits were 10 ng/mL for amphetamine and methamphetamine and 20 ng/mL for MDA and MDMA. All of these data recommend the applicability of the method for use in the analytical routine of a forensic laboratory.

Mephedrone: use, subjective effects and health risks.

AIMS: To assess the patterns of use, subjective effect profile and dependence liability of mephedrone, supported by corroborative urine toxicology. DESIGN: Cross-sectional structured telephone interview. SETTING: UK-based drug users associated with the dance music scene. PARTICIPANTS: A total of 100 mephedrone users, recruited through their involvement with the dance music scene. MEASUREMENTS: Assessment of pattern of use, acute and after effects, DSM dependence criteria and gas chromatography-mass spectrometry urinalysis. FINDINGS: Mephedrone consumption results in typical stimulant-related subjective effects: euphoria, increased concentration, talkativeness, urge to move, empathy, jaw clenching, reduced appetite and insomnia. Thirty per cent of the sample potentially met criteria for DSM-IV dependence and there was evidence of a strong compulsion to use the drug (47% had used the drug for 2 or more consecutive days). Self-reported recent consumption of mephedrone was confirmed by toxicological analysis in all of the 14 participants who submitted a urine sample. CONCLUSION: Mephedrone has a high abuse and health risk liability, with increased tolerance, impaired control and a compulsion to use, the predominant reported dependence symptoms.

Mixed-bed polymeric o-nitrobenzophenone reagents for the on-line derivatization of amines in high performance liquid chromatography.

Several polymer-bound o-nitrobenzophenone reagents containing different detector-sensitive tags have been combined in the same reactor for the on-line derivatization of amine samples. The formation of multiple derivatives allows numerous opportunities for quantitation from the same injection, and also allows improved identification from the retention times of the multiple derivatives. Changing the reaction conditions changes the ratio of the products formed, so that changes in the ratio of peak heights and areas can also be used for analyte identification. In this work, propylamine was derivatized in acetonitrile on-line, precolumn. Changing the reaction conditions, of reaction time, temperature, solvent, presence of catalyst and the components of the reactor, changed the ratio of the derivatives formed. These changes in product formation with changing reaction conditions were applied to the identification and quantitation of amphetamine and methamphetamine in urine. The drugs were identified by the retention times of their derivatives, the ratio of the peak areas of the derivatives and the change in the ratios after changing reaction conditions. Each derivative was also used for quantitation of levels of spiked concentrations of amphetamine and methamphetamine, with relative errors less than 8%.

Automated HPLC analyses of drugs of abuse via direct injection of biological fluids followed by simultaneous solid-phase extraction and derivatization with fluorescence detection.

An automated system is described for the simultaneous extraction and derivatization of nucleophilic compounds from various biological media. The method includes the use of a solid-phase reagent containing a 9-fluorenylacetate activated ester. The reagent is based on a controlled pore, polystyrene divinylbenzene support prepared through a silica template procedure. An X-Y-Z robotic arm equipped with a needle is used in conjunction with a syringe pump for aspirating and dispensing samples and standards into the HPLC system. A precolumn cartridge containing the solid-phase reagent is put on-line in place of the fixed-volume injection loop. Injections of biological fluids such as urine or plasma with minimal sample treatment and handling are made directly into this reactor. The analytes are derivatized as they are extracted, allowing virtually unlimited sample volumes to be injected. The polymeric cartridge can be used for up to 100 injections without accruing unacceptable reductions in sensitivity. A detection limit of 500 p.p.t. (parts per trillion) of amphetamine in urine was achieved with this system.

Homogeneous, micelle quenching fluoroimmunoassay for detecting amphetamines in urine.

We developed a homogeneous fluoroimmunoassay for detecting amphetamines in urine. Only fluorescence intensity need be measured because the emission of non-protein-bound fluorescein-labeled amphetamine is preferentially quenched by detergent micelles. In a previous reported prototype assay system for measuring gentamicin in serum we used fluorescein and dodecyl sulfate (Anal Chem 1985; 57:1928-30). We have found that favorable hydrophobic and (or) ionic character of the analyte and unfavorable polar and (or) ionic character of the fluor are important determinants of the desired interactions. An anionic detergent and fluorescein, therefore, should be appropriate for apolar of cationic analytes, such as gentamicin and amphetamines. A greater [H+] at the anionic micelle surface is important for quenching emission from the fluor moiety. Millimolar concentrations of dodecyl sulfate rapidly denature immunoglobulin unless hapten is bound with sufficiently high affinity. Affinity was sufficiently high for the antibody used in the prototype gentamicin assay but not for the amphetamine antibody. Thus for the amphetamine assay, we used a non-denaturing detergent, dodecyl(oxyethylene)12 sulfate. The assay requires 30 microL of specimen in 2 mL of total assay volume. Amphetamine(d-,dl-, and meth-), at a concentration of 1 mg per liter of urine, is readily detected.