The application of capillary electrophoresis for enantiomeric separation of N,N-dimethylamphetamine and its related analogs: intelligence study on N,N-dimethylamphetamine samples in crystalline and tablet forms

This paper reports a new capillary zone electrophoresis method for the simultaneous chiral determination of the enantiomers of N,N-dimethylamphetamine (DMA), methamphetamine (MA), ephedrine (E), pseudoephedrine (PE) and methylephedrine (Me-E). In this study, a number of electophoretic parameters were examined and optimized including the choice of chiral selectors, the use of short-chain tetraalkylammonium cations, the effect of chiral selector concentration, buffer concentration, applied voltage and capillary temperature. Heptakis(2,6-di-O-methyl)-beta-cyclodextrin (DM-beta-CD) and tetrabutylammonium (TBA) being the best chiral selector and buffer cation, respectively, the optimized electrophoretic conditions were found to be: 20 mM DM-beta-CD, 50 mM TBAPO(4) at pH 2.5, applied voltage at 30 kV and temperature at 25 degrees C. Under the optimized conditions, all analytes were well separated with resolution factors between 3.3 and 24.0 achieved. Using phentermine as an internal standard, the intra-day (n=8) precisions for the relative migration times and peak areas of all analytes were below 1.09%, while the inter-day precisions (n=12, 6 days) for the relative migration times and peak areas of all analytes were under 3.77%. This method has been applied to the measurement of the enantiomeric purities of the seized DMA samples. The result of the measurement could provide important clues about the possible synthetic pathways of these samples.     

Optimization of a simple method for the chiral separation of methamphetamine and related compounds in clandestine tablets and urine samples by beta-cyclodextrine modified capillary electrophoresis: a complementary method to GC-MS

The chiral separation of (+/-)-methamphetamine, (+/-)-methcathinone, (+/-)-ephedrine and (+/-)-pseudoephedrine by means of beta-cyclodextrine modified capillary electrophoresis is described. The distribution of enantiomers in clandestine tablets and urine samples were identified. Several electrophoretic parameters such as the concentration of beta-cyclodextrin, temperature, the applied voltage and the amount of organic solvent required for successful separation were optimized. The method, as described herein, represents a good complementary method to GC-MS for use in forensic and clinical analysis.     

Development of a capillary zone electrophoresis method including a factorial design and simplex optimisation for analysis of amphetamine, amphetamine analogues, cocaine, and heroin

A capillary zone electrophoresis (CZE) method was developed for the analysis of amphetamine and 13 amphetamine analogues. A full factorial design was used to screen for important design variables (i.e. carrier electrolyte concentration, pH, and separation temperature), and a modified simplex was employed in a final optimisation step. The resolution values of the target compounds were used as responses in the screening and optimisation phases. This approach made it possible to control the effects of the design variables on the separation of the target compounds. The best results were obtained using a 100mM Tris/phosphate buffer (pH 3.1) at a separation temperature of 10 degrees C, and the analysis time was 23 min under these conditions. After slight modification, the method also enabled baseline resolution of the most commonly encountered amphetamine derivatives, as well as cocaine and heroin, within 7 min. There was a linear relationship between peak area and concentration for all substances, with correlation coefficients in the range of 0.9975-0.9999. Moreover, the technique was repeatable and exhibited relative standard deviation (R.S.D.) values in the ranges of 0.01-0.11% and 0.54-1.60% for relative migration time and corrected peak area, respectively. Lastly, the method was successfully applied to analyse street samples.     

Optimization of the separation of organic explosives by capillary electrophoresis with artificial neural networks

The separation of 12 explosives by capillary electrophoresis was optimized with the aid of artificial neural networks (ANNs). The selectivity of the separation was manipulated by varying the concentration of sodium dodecyl sulfate (SDS) and the pH of the electrolyte, while maintaining the buffer concentration at 10 mM borate. The concentration of SDS and the electrolyte pH were used as input variables and the mobility of the explosives were used as output variables for the ANN. In total, eight experiments were performed based on a factorial design to train a variety of artificial neural network architectures. A further three experiments were required to train ANN architectures to adequately model the experimental space. A product resolution response surface was constructed based on the predicted mobilities of the best performing ANN. This response surface pointed to two optima; pH 9.0-9.1 and 60-65 mM SDS, and pH 8.4-8.6 and 50-60 mM SDS. Separation of all 12 explosives was achieved at the second optimum. The separation was further improved by changing the capillary to an extended cell detection window and reducing the diameter of the capillary from 75 microm to 50 microm. This provided a more efficient separation without compromising detection sensitivity.     

Simultaneous separation of different types of amphetamine and piperazine designer drugs by capillary electrophoresis with a chiral selector

The recent emergence of a new class of piperazine-type compounds has brought about the need for laboratory screening methods for both seized drugs and toxicological samples. These piperazine compounds, which include 1-benzylpiperazine (BZP) and 1-(3-trifluoromethylphenyl)piperazine (TFMPP), exhibit comparable physiological effects and can be substituted for the classic amphetamine-type drugs. We have optimized a chiral capillary electrophoresis (CE) separation that detects a set of 6 piperazine and 4 chiral amphetamine compounds in under 23 min using a 200 mM phosphate buffer at a pH = 2.8 with 20 mM hydroxypropyl- beta-cyclodextrin (HPbeta3CD). In addition to the above compounds, a series of "clandestine" BZP diHCl samples were also analyzed using this method to assess the ruggedness of the procedure. The novel CE separation was tailored to simultaneously detect these piperzine compounds in addition to amphetamine-type drugs. Distinct migration time and UV-spectral data were obtained for all compounds of interest.     

Use of dynamically coated capillaries for the routine analysis of methamphetamine, amphetamine, MDA, MDMA, MDEA, and cocaine using capillary electrophoresis

A rapid, accurate, precise, reproducible, economical, and environmentally gentle method using capillary electrophoresis (CE) is presented for the routine analysis of methamphetamine, amphetamine, MDA, MDMA, MDEA, and cocaine in seized drugs. The methodology uses a 32 cm by 50 microm capillary (length to detector 23.5 cm) with a commercially available buffer kit and diode array UV detection. Dynamic coating of the capillary surface is accomplished by flushing with base for 1 min, a proprietary polycation for 1 min, and then a proprietary polyanion for 2 min. This approach provides a relatively high and stable electroosmotic flow (EOF), even at low pHs. The background electrolyte (BGE) contains 75 mM phosphate buffer (pH 2.5) with the same polyanion as above. Using this methodology, amphetamine, methamphetamine, MDA, MDMA, MDEA, and an internal standard (n-butylamphetamine) are baseline resolved in less than 5 min. The run-to-run migration time %RSDs and peak area %RSDs are typically <0.3% and <2.1%, respectively. The day-to-day and capillary-to-capillary migration time %RSDs are <1.5% and <2.1%, respectively. The %RSDs of the relative migration times compared with the internal standard on a day-to-day and capillary-to-capillary basis are <0.2% and <0.06%, respectively. The linear dynamic range using peak areas range from 0.003 to 0.10 mg/mL. The correlation coefficients are >0.9998, with all calibration curves passing at or near the origin. Similar data are obtained for cocaine and its internal standard henyltoloxamine. None of the compounds usually encountered in illicit samples interfere with the target compound (e.g., methamphetamine and cocaine) or the internal standard. Quantitative results for synthetic mixtures and seized exhibits are in good agreement with actual values, and also with results obtained from other techniques. The relatively high EOF for the dynamically coated capillary system allows for the screening of basic, acidic, and neutral adulterants in drug seizures; identification is facilitated by the use of automated UV library searches.     

Evaluation of sieving polymers for fast, reproducible electrophoretic analysis of short tandem repeats (STR) in capillaries

Efficient capillary electrophoretic STR analysis requires rapid, reproducible and robust separation of DNA fragments with reasonable capillary longevity--this is currently accomplished using proprietary commercial polymeric sieving matrices specifically developed for this separation. These matrices, while effective, are costly and do not provide adequate resolution of STR DNA fragments in capillaries with shorter effective separation lengths, increasing the time required to accomplish the separation and minimizing the potential extrapolation to other miniaturized platforms. As the forensic community looks toward next generation microchip technology as a means of processing casework more rapidly, new sieving polymers need to be evaluated for utilization in this platform. The research presented here describes the assessment of commercially-available polymeric sieving matrices for STR analysis, with consideration given to feasibility of incorporation into a microdevice. Polymer composition, molecular weight, and concentration were evaluated, along with an assessment of the effects of buffer composition, separation temperature, and capillary length. These variables were evaluated individually or collectively on the ability to resolve STR DNA fragments and the reproducibility of the separations and the results compared to a proprietary commercial product. A 600,000 Da MW poly(ethylene oxide) (PEO) solution at a 3% (w/v) concentration was determined to be the most suitable matrix for these separations. This polymer, in coated capillaries, provided highly robust and reproducible separations, with near baseline resolution of fragments having single base differences. Reductions in the temperature of the separation, from 60 degrees C to 40 degrees C, and the urea concentration of the buffer, from 7 M to 3.5 M, provided increased longevity of the PEO polymer for repeated separations. Comparison of this polymer with currently specified commercial products used for STR analysis showed that the optimized PEO matrix provided superior separations under all conditions tested. In addition, PEO could be utilized in shorter capillary systems, with a concurrent decrease in analysis time, highlighting its potential for use in shortened capillary or microdevice systems.     

Capillary electrophoretic analysis of phosphorus species in clandestine methamphetamine laboratory samples

The clandestine manufacture of methamphetamine is a spreading epidemic. Manufacturing methods are constantly changing, necessitating the implementation of new analytical tools to identify materials from these labs. Characterization of phosphate, phosphite, and hypophosphite ions is necessary to distinguish the various phosphorus-iodine manufacturing methods that are popular methods for reducing pseudoephedrine to methamphetamine. This work describes a capillary electrophoresis method to separate acetate, azide, bromide, carbonate, chlorate, chloride, chromate, fluoride, hypophosphite, iodide, nitrate, nitrite, perchlorate, phosphate, phosphite, sulfate, sulfite, and thiocyanate. The CElixerOA 8.2 dynamic coating system was modified by lowering the capillary temperature to 15 degrees C and using an acid flush between runs to remove adsorbed materials. This allows detection of ions down to between 10 and 30 parts per million with percent relative standard deviations of normalized migration times under 0.1%. This method is a valuable tool for the characterization of phosphate, phosphite, and hypophosphite in routine analysis of clandestine methamphetamine manufacturing evidence and has a broader application in other areas of forensic analysis.     

The rapid analysis of heroin drug seizures using micellar electrokinetic chromatography with short-end injection

A simple and rapid method for the analysis of heroin seizures by micellar electrokinetic chromatography with short-end injection is described. Separations were performed using an uncoated fused silica capillary, 50 cm x 50 microm I.D. x 360 microm O.D. with an effective separation length of 8 cm. The system was run at 25 degrees C with an applied negative voltage of -25 kilovolts. Injection of each sample was for 2 s at -50 mbar. UV detection was employed with the wavelength set at 210 nm. The background electrolyte consisted of 85:15 (water:acetonitrile, v/v) containing final concentrations of 25 mM SDS and 15 mM sodium borate, pH 9.5. Samples and standards were prepared in 0.1% v/v acetic acid and diluted in the run buffer containing 1 mg/ml of N,N-dimethyl-5-methoxytryptamine as an internal standard. Under these conditions a text mixture containing caffeine, paracetamol, morphine, codeine, heroin, and acetylcodeine was resolved within 1.5 min. The method was used to determine the concentration of heroin in heroin seizure samples, and the results were in good agreement with those obtained by a validated gas chromatographic method.     

Rapid determination of carbohydrates in heroin drug seizures using capillary electrophoresis with short-end injection

A simple and rapid method for the analysis of carbohydrates in heroin samples by capillary electrophoresis utilizing a borate complexation method is described. Separations were performed using an uncoated fused silica capillary, 50 cm x 50 micro I.D. x 360 microm O.D. with an effective separation length of 9 cm. The system was run at 60 degrees C with an applied voltage of -8 kilovolts. Injection of each sample was for 1 sec at -50 mbar. UV detection was employed with the wavelength set at 195 nm. The background electrolyte consisted of 65 mM borate, pH 12.0. Samples and standards were prepared in the run buffer containing 2 mg/mL of mannose as an internal standard. Under these conditions a test mixture containing glucose, sucrose, lactose, mannitol and mannose as an internal standard was resolved within 5 min. The method was used to determine the concentration of carbohydrates in heroin seizure samples and synthetic heroin samples. The results were in good agreement with the reported values.     

Forensic application of chiral separation of amphetamine-type stimulants to impurity analysis of seized methamphetamine by capillary electrophoresis

The applicability of capillary electrophoresis (CE) with a UV detector using highly sulfated gamma-cyclodextrin as a chiral selector was examined for analysis of impurities in seized methamphetamine. Samples of methamphetamine-hydrochloride dissolved in water at a high concentration (20 mg/mL) were analyzed. Electrokinetic injection has an advantage over hydrodynamic injection for improving the detection of trace impurities. Small peaks of the precursor impurities, such as (1R,2S)-(-)-ephedrine and (1S,2S)-(+)-pseudoephedrine, were detected and quantified without extraction. The seized drugs could be classified into three groups based on the contents of the two impurities.     

Development and validation of a liquid chromatography-tandem mass spectrometry assay for hair analysis of atomoxetine and its metabolites: Application in clinical practice

Atomoxetine (ATX) is a potent inhibitor of the noradrenaline reuptake transporter approved since 2002 for the treatment of attention-deficit/hyperactivity disorder (ADHD) in children, adolescents, and adults as alternative treatment to methylphenidate. A procedure based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of ATX and its main metabolites (4-hydroxyatomoxetine - 4 hydroxyATX - and N-desmethylatomoxetine - des-methylATX) in hair of one treated child and five treated adolescents. Since hair samples can be easily collected without the need for specials skills and exposing a patient to discomfort, hair testing of ATX and eventually of its metabolites should be useful, especially in case of pediatric patients, to check compliance in a wider time-window. After addition of duloxetine as internal standard, hair samples were overnight digested with 2ml 1M NaOH at 45°C. Then, analytes were extracted from alkaline solution with two different 2ml aliquots of tert-butyl methyl ether. Chromatographic separation was achieved at ambient temperature using a reverse-phase column and a mobile phase of 40% of water-60% 5mM ammonium acetate, 50mM formic acid, 4mM trifluoroacetic acid in acetonitrile-water (85:15, v/v). The mass spectrometer was operated in positive ion mode using multiple reaction monitoring. The method was linear over the concentration range 0.2-50ng/mg hair for the all analytes under investigation, with an intra- and inter-assay imprecision and inaccuracy always less than 20% and an analytical recovery between 33.1% and 76.1%, depending on the considered analyte. Only ATX and 4-hydroxyATX were detected in hair samples with concentrations varying from 0.2 to 2.0ng/mg hair and from 0.3 to 1.0ng/mg, respectively. Notwithstanding the absence of any dose-hair concentration relationship, hair monitoring of ATX and concomitant medications commonly administrated in ADHD children and adolescents can be crucial in verifying long-term compliance to prescribed medication in individuals displaying a non negligible tendency to refuse drugs and to lie on the adherence to therapy as a specific symptom of the disease.     

Immunoassay for methamphetamine with a new antibody

p- and o-Aminomethamphetamine were synthesized as haptens to be coupled with carrier protein at the benzene ring of methamphetamine. Immunogens were prepared by the glutaraldehyde method or the MBS (N-(m-maleimidobenzoyloxy)succinimide) type cross-linking reagent method. In particular, immunization with p-aminomethamphetamine-bovine serum albumin (BSA) conjugate prepared by the glutaraldehyde method gave an anti-methamphetamine antiserum having a low cross-reactivity with methylephedrine. With the antiserum, three kinds of immunoassays for methamphetamine were established. An enzyme immunoassay (EIA) and an enzyme-linked immunosorbent assay (ELISA) were developed with alkaline phosphatase (ALP) as a label enzyme. The amount of antibody bound ALP conjugate was determined by its activity in dephosphorylating p-nitrophenyl phosphate in EIA and nicotinamide adenine dinucleotide phosphate (NADP+) in ELISA. The range of methamphetamine measurable by ELISA was 0.025-0.5 ng/well and its sensitivity was superior to that of EIA (0.3-300 ng/tube). A latex agglutination inhibition reaction test (LAIRT) was also developed for the mass screening method of urine samples. The sensitivity of this method for methamphetamine was 0.1 micrograms/ml urine.     

Rapid Separation of Organophosphate Pesticides using Micellar Electrokinetic Chromatography and Short‐end Injection,

Organophosphate (OP) pesticides are highly toxic substances and are frequently represented as poisons. In order to qualify and quantify the selected OP pesticides (methyl paraoxon, ethyl paraoxon, methyl parathion, fenitrothion, and ethyl parathion), micellar electrokinetic chromatography and short‐end injection were investigated. This is the first time that this combination has been used to separate OP pesticides. A capillary with 8.5 cm effective length was used, and the analytes were separated within 2.1 min. Separation conditions including buffer (type, pH, and concentration), sodium dodecyl sulfate concentration, and separation voltage were optimized. The limit of detection (LOD) was estimated in the range of 10–20 μM. The OP pesticides spiked in artificial saliva and drinking water gave superior peak profiles, and good average recoveries 95.6% and 62.3%, respectively. Overall, a rapid method with excellent resolution and efficiency was developed and successfully applied in the analysis of potential sample matrixes.     

Direct effects of methamphetamine on hypertrophy and microtubules in cultured adult rat ventricular myocytes

Morphological alterations occasionally found in the myocardium of methamphetamine (MAP) abusers include hypertrophy, atrophy, disarrangement of myofibrils and fibrosis. These cardiac alterations have been thought to be due to an indirect action of MAP via catecholamines released by MAP administration. However, the direct effect of MAP on cardiomyocytes is not clear. In previous studies, we showed that cell size of isolated adult rat ventricular cardiomyocytes (ARCs) exposed to MAP was larger than that of untreated cells in culture supplemented with 10% fetal calf serum (FCS). In this study, to determine further the direct effect of MAP on cardiomyocytes, cultured ARCs were exposed to 0.05, 0.1 and 0.5 mM MAP for 7 days in culture medium without FCS following 6-day normal culture in medium containing FCS. Myocyte size was measured and microtubular (MT) structures which were associated with functional disorder of hearts were immunohistochemically observed using confocal microscopy. The size in treated ARCs significantly increased time- and dose-dependently as compared with untreated cells, but it decreased 7 days after exposure to 0.5 mM MAP. The increases in cell size, however, were lower than that in serum-supplemented cultures. MT structures in intact ARCs appeared as a filamentous network throughout the cytoplasm and around the nucleus. MAP exposure for 3 days promoted MT assembly, but in 7-day treated cells, MT and actin structures were injured. These results suggested that MAP directly induced cellular hypertrophy and might lead to cardiac functional disorder.     

Identification of N,N-dimethylamphetamine formed by methylation of methamphetamine in formalin-fixed liver tissue by multistage mass spectrometry

Methamphetamine is methylated in the presence of unbuffered formalin solutions within hours at room temperature. The product, N,N-dimethylamphetamine, is also found in human liver exposed to methamphetamine followed by incubation with formalin. In the present study, a direct mass spectrometric method was developed to identify N,N-dimethylamphetamine in human liver before and after treatment with formalin. Human liver samples were obtained from four deaths that were investigated by the West Virginia Office of Chief Medical Examiner. Full toxicological analysis was conducted on samples from the decedents and methamphetamine was among the positive findings in each case. The method used to expose liver tissue to formaldehyde involved treating a small piece of liver from each case with formalin solution (20% v/v) for 24 h at room temperature. The formalin treated tissues were homogenized and the resulting suspension was sonicated for 5 min, and then centrifuged. Supernatant aliquots were directly analyzed by electrospray ionization (ESI) mass spectrometry without chromatographic isolation. Positive ion multistage mass spectra recorded in MS, MS/MS and MS/MS/MS (MS3) modes were used to confirm the presence of N,N-dimethylamphetamine and methamphetamine in the mixture. Liver tissue not treated with formalin did not contain a detectable level of N,N-dimethylamphetamine. Decreases in methamphetamine concentrations in liver tissue resulting from treatment with formalin were measured using deuterium-labeled methamphetamine as internal standard. The method can be completed in less than 2 h on thawed tissue. The results suggest that the process of fixing tissues with formalin may lead to false negative findings for methamphetamine.     

The Optimization of Electrophoresis on a Glass Microfluidic Chip and its Application in Forensic Science

Microfluidic chips offer significant speed, cost, and sensitivity advantages, but numerous parameters must be optimized to provide microchip electrophoresis detection. Experiments were conducted to study the factors, including sieving matrices (the concentration and type), surface modification, analysis temperature, and electric field strengths, which all impact the effectiveness of microchip electrophoresis detection of DNA samples. Our results showed that the best resolution for ssDNA was observed using 4.5% w/v (7 M urea) lab‐fabricated LPA gel, dynamic wall coating of the microchannel, electrophoresis temperatures between 55 and 60°C, and electrical fields between 350 and 450 V/cm on the microchip‐based capillary electrophoresis (μCE) system. One base‐pair resolution could be achieved in the 19‐cm‐length microchannel. Furthermore, both 9947A standard genomic DNA and DNA extracted from blood spots were demonstrated to be successfully separated with well‐resolved DNA peaks in 8 min. Therefore, the microchip electrophoresis system demonstrated good potential for rapid forensic DNA analysis.     

Comparative analysis of gamma-hydroxybutyrate and gamma-hydroxyvalerate using GC/MS and HPLC

This paper describes two analytical techniques used to separate and quantify gamma-hydroxybutyrate (GHB) and gamma-hydroxyvalerate (GHV). The first technique was a N,O-bis(trimethylsilyl)triflouro-acetimide-trimethylchlorosilane derivatization, followed by gas chromatography/mass spectrometry analysis using an HP-5 capillary column at a rate of 1.0 mL/min with a run time of 9.25 min. This technique was found to be sensitive (LOD 1 pg on column) and gave a low average error (5%) in a beverage study. When supplemented by a surrogate spike, the method yielded 97% analyte recovery from beverages. The second technique was high-performance liquid chromatography/UV (HPLC/UV) using a C-18 column with a (20:80% v/v) methanol:dibasic phosphoric buffer (10 mM, pH 3) at a rate of 1.00 mL/min with a run time of 7.5 min. UV detection occurred at 254 nm. This method was found to be less sensitive (LOD 0.05 microg on column) for direct analysis of aqueous samples. To remove interferences seen in the beverage study, a liquid-liquid extraction before HPLC analysis was tested. However, a decreased sensitivity (LOD 100 microg on column) and irreproducible peak profiles resulted.     

SPME-GC-MS法快速检测尿液中的甲基苯丙胺

目的建立SPME-GC-MS快速检测吸毒人员尿液中的甲基苯丙胺的方法。方法以SPME法提取尿液中的甲基苯丙胺,以1-萘胺作内标,用GC-MS法检测。结果在2～2000ng/mL的范围内呈线性关系(r=0.9985,n=7),甲基苯丙胺的检测限为0.5ng/mL(信噪比3),在低、中、高(200、500、1000ng/mL)浓度的平均相对回收率为102.6%、98.5%、93.2%,日内及日间RSD分别小于8.1%、7.2%。结论用此方法检测尿液中的甲基苯丙胺,灵敏度高,简单快速,易操作,适用于吸毒人员的快速定性定量检测。