Development of microwave-assisted extraction procedure for organic impurity profiling of seized 3,4-methylenedioxymethamphetamine (MDMA)

Abstract: Organic impurity profiling of seized 3,4‐methylenedioxymethamphetamine (MDMA) tablets aims to link tablets to common production sources. Conventionally, organic impurities are extracted from tablets using a liquid–liquid extraction (LLE) procedure prior to analysis by gas chromatography–mass spectrometry (GC‐MS). In this research, the development of an alternative microwave‐assisted extraction/headspace solid‐phase microextraction (MAE/HS‐SPME) procedure is described. The optimal procedure used phosphate buffer (1 M, pH 8), with an HS‐SPME extraction temperature of 70°C for 40 min, using a divinylbenzene/Carboxen?/polydimethylsiloxane (DVB/CAR/PDMS) fiber. Impurities were extracted from seized MDMA exhibits using the MAE/HS‐SPME procedure, as well as HS‐SPME alone, and a conventional LLE procedure. The HS‐SPME procedure was deemed to be the most practical because of the affordability and need for less analyst involvement. Although the LLE was limited in the number of impurities extracted, the procedure is still useful for the extraction of less volatile impurities that are not extracted by HS‐SPME.     

Comparison and classification of methamphetamine seized in Japan and Thailand using gas chromatography with liquid-liquid extraction and solid-phase microextraction

Methamphetamine (MA) is one of the most frequently abused drugs worldwide. The aim of this study is to improve the analytical method for profiling MA impurity in order to compare and classify MA crystals seized in different countries and to investigate the relationships between seizures. To compare MA samples seized in Japan and Thailand, the following analytical method was adopted. A 50mg sample of MA.HCl was dissolved in 1ml of buffer solution (four parts 0.1M phosphate buffer, pH 7.0, and one part 10% Na(2)CO(3)), impurities were extracted with 0.5ml of ethyl acetate containing four internal standards (n-decane, n-pentadecane, n-eicosane and n-octacosane) and analyzed by gas chromatography with a flame ionization detector on a DB-5 capillary column (0.32mm i.d.x30m, film thickness 1.0mum). Fourteen characteristic peaks on chromatograms were selected for the comparison and classification of samples, and the data were evaluated by the Euclidean distance of the relative peak areas after logarithmic transformation. Sixty-nine samples seized in Japan and 42 seized in Thailand were analyzed. The samples were classified into four groups roughly by cluster analysis. In addition, when it was difficult to compare samples that had fewer impurities on chromatograms obtained from liquid-liquid extraction (LLE), solid-phase microextraction (SPME) was effective. Because many characteristic peaks were detected using SPME, SPME made it easy to compare samples of high purity. The combination of LLE and SPME was useful for impurity profiling of MA samples seized in different countries.     

Identification of impurities and the statistical classification of methamphetamine using headspace solid phase microextraction and gas chromatography-mass spectrometry

The profiling of impurities in methamphetamine (MA) using headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) is described. The extraction of the impurities with an SPME fiber was examined under varying conditions. Optimal chromatograms were obtained when a 50 mg MA sample at 85 degrees C for 30 min was extracted using a fiber coated with divinylbenzene/carboxen/polydimethylsiloxane. MA samples from nine different origins were analyzed under optimized extraction conditions. Compounds related to MA such as benzaldehyde, benzyl alcohol, amphetamine, benzyl methyl ketone, cis- and trans-1,2-dimethyl-3-phenylaziridine, dimethylamphetamine, N-acetylamphetamine, N-acetylmethamphetamine and N-formylmethamphetamine were detected in the chromatograms. Trace amounts of ethanol, diethyl ether and acetic acid were also detected in some of the chromatograms. The numbers and intensities of the peaks detected were different, depending on the sample. After the areas of the eight principal peaks were converted to their square root and logarithm, similarities among the samples were evaluated by Euclidian distance, cosine distance and correlation coefficient. The results showed that a combination of logarithmic conversion and cosine distance was the most suitable for discriminating and classifying the samples. HS-SPME/GC-MS is a simple and effective method for the extraction and identification of impurities. The present method, in combination with an appropriate statistical analysis, would be useful for developing a profile of impurities in MA.     

Contribution of thermal desorption and liquid-liquid extraction for identification and profiling of impurities in methamphetamine by gas chromatography-mass spectrometry

Impurity profiling of methamphetamine (MA) using thermal desorption (TD) and gas chromatography-mass spectrometry (GC-MS) was examined. Using TD/GC-MS, impurities were extracted and separated under various conditions. Optimal chromatograms were obtained when a 20 mg MA sample was extracted at 120 degrees C for 3 min using a TD instrument, followed by separation of the extracts using a non-polar capillary column coated with (5%phenyl)-methylpolysiloxane. MA samples from nine different batches were analyzed under optimized conditions. Compounds related to the structure of MA, such as benzaldehyde, benzyl alcohol, amphetamine, cis- and trans-1,2-dimethyl-3-phenylaziridine, dimethylamphetamine, and N-acetylephedrine, were detected in the chromatograms without any laborious extraction procedure. Compounds such as ethanol, diethyl ether, and acetic acid, which are considered reagents and solvents for MA synthesis, were also detected in some of the chromatograms. The numbers and intensities of the peaks detected were different among the samples. Impurity profiling of MA using TD was compared with that using liquid-liquid extraction (LLE). Better reproducibility of peak areas was obtained using LLE, whereas higher intensities and numbers of peaks were detected using TD. Solvents were extracted more effectively using TD. The nine batches of MA were classified using both extraction procedures. The nine batches were divided roughly into two groups using data from LLE. Subsequently, the groups were classified in detail using data from TD. TD can be used to provide supplemental information for LLE, and the combination of these extraction methods can be helpful for impurity profiling of MA.     

Optimum methamphetamine profiling with sample preparation by solid-phase microextraction

Solid-phase microextraction (SPME) is a relatively new technique in which a small, polymer-coated fiber is employed to extract volatile and semivolatile organic compounds from the sealed headspace above a questioned sample. SPME, coupled with gas chromatography/mass spectrometry (GC/MS), was used to characterize impurities in illicit methamphetamine samples. Trace impurities present in a specimen were tentatively identified using mass-spectral databases and included 1,2-dimethyl-3-phenyl-aziridine (indicating synthesis via a halogenated ephedrine intermediate), ethyl vanillin (a flavoring compound), and caffeine (a stimulant used as cutting agent). The types and numbers of organic compounds sampled by SPME were compared with those collected by various solvent extraction protocols. In addition to unambiguously confirming the presence of methamphetamine, SPME-GC/MS analyses detected approximately 30 more organic analytes than were found by GC/MS following the ethyl acetate extraction method adopted by the United Nations International Drug Control Programme. SPME-GC/MS is a superior method for generating material "fingerprint" profiles in methamphetamine samples. The detection and characterization of increased points of comparison in drug samples provide more detailed chemical signatures for both intelligence and operational information.     

Drug intelligence based on organic impurities in illicit MA samples

One major objective of the European project "Collaborative Harmonisation of Methods for Profiling of Amphetamine Type Stimulants" (CHAMP), funded by the sixth framework programme of the European Commission, consisted of the harmonisation of a gas chromatography/mass spectrometry (GC/MS) method for the analysis of organic impurities found in illicit methamphetamine (MA) samples in a drug intelligence perspective. Statistical analysis provided a selection of pertinent variables among the 43 organic impurities identified in the chromatograms. As for the 3,4-MethyleneDioxyMethAmphetamine (MDMA) study, correlation coefficients were used as a discrimination tool between populations of linked samples (from the same seizure) and unlinked samples (from different seizures). It was also shown that correlation measurements based on Pearson and cosine functions applied to the data pre-treated by normalisation to the sum of peak responses followed by the square root provided excellent discrimination between the two populations. The organic impurities profiling method was proved to be relevant for the characterization of samples from different seizures and their synthesis route patterns.     

生物检材中甲基苯丙胺及苯丙胺的分析研究进展

对近几年国内外22篇有关生物检材中甲基苯丙胺及苯丙胺测定的文献进行了综述。介绍了血、尿、毛发等生物检材的收集与预处理方法,比较了生物检材中甲基苯丙胺及苯丙胺的液-液萃取(LLE)、固相萃取(SPE)、固相微萃取(SPME)和顶空固相微萃取(HS-SPME)等提取方法,以及内标的选取、不同的衍生化方法和包括免疫、GC/MS、GC/NPD、GC/ECD、GC/FID、HPLC、HPCE在内的各种检测方法。最后,对分析结果的评定进行了讨论。     

SPME/GC-MS characterization of volatiles associated with methamphetamine: toward the development of a pseudomethamphetamine training material

The headspace profiles of eleven methamphetamine (MA) samples have been analyzed using solid-phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). Nine of the eleven are illicit MA seizures from the Southwest U.S. border. One sample is methamphetamine base synthesized in the Drug Enforcement Administration (DEA) Southwest Laboratory, and the remaining sample is pharmaceutical-grade methamphetamine hydrochloride that is used to make training aids for drug detecting canines. In addition. volatiles associated with 1-phenyl-2-propanone (P2P), a methamphetamine precursor, have been identified for comparison with those found in methamphetamine seizure and the two reference samples. Eighty-seven different compounds were identified from all the samples, not including simple hydrocarbons and aldehydes. Only seven occur consistently in all seizure samples, and these are: acetic acid, benzaldehyde, acetophenone, P2P, 1-phenyl-1,2-propanedione (P12P), 3-phenyl-3-buten-2-one, 1-chloro-1-phenyl-2-propanone. Dimethyl sulfone, a common cutting agent in methamphetamine. was found in six of the nine seizure materials. When the reference methamphetamine and P2P samples are included, only two compounds are common to all twelve samples, and these are benzaldehyde and P2P. As such, these two compounds are likely candidates for use in a pseudomethamphetamine (PM) formulation, and their effectiveness in eliciting a canine response is being evaluated before actual deployment.     

Effect of Extraction Procedure and Gas Chromatography Temperature Program on Discrimination of MDMA Exhibits

Analysis of impurities in seized MDMA tablets can be used to determine the synthesis method used and to identify links among exhibits. However, no standardized method exists to generate impurity profiles, limiting comparisons among different laboratories. This research investigated the effect of extraction procedure and gas chromatography temperature program on the resulting impurity profiles. Five exhibits were extracted using liquid–liquid extraction (LLE) and headspace solid‐phase microextraction (HS‐SPME), then analyzed using two different temperature programs. Profiles were statistically assessed using principal components analysis. While LLE was more reproducible, more compounds were extracted using HS‐SPME, thus providing more informative chemical profiles. The longer temperature program (53 min vs. 36 min) allowed greater discrimination of exhibits, due to improved precision as a result of an extended hold time (12 min). This research further highlights the need for standardized extraction and analysis procedures to allow comparison of chemical profiles generated in different laboratories.     

分子印迹固相萃取法在血中苯丙胺类毒品分析中的应用

目的建立分子印迹固相萃取（MISPE）、GC/MS分析方法,用于血液中苯丙胺类毒品检测。方法 10mmol/L醋酸铵缓冲液（pH8.0）4倍稀释空白添加血液,1mL甲醇,1mL10mmol/L醋酸铵缓冲液（pH8.0）活化苯丙胺类分子印迹固相萃取柱;2×1mL去离子水、1mL60%的乙腈去离子水、1mL1%醋酸乙腈洗涤杂质;2×1mL1%甲酸/甲醇洗脱,洗脱液挥干定容,经GC/NPD、GC/MS分析检测。结果各种苯丙胺类毒品回收率均在90%以上,在20～5 000ng/mL浓度范围内线性关系良好,r2为0.995 7～0.998 9,LOQ在16～30ng/mL之间,LOD在8～15ng/mL之间。结论本方法回收率高,净化效果显著,稳定性好,杂质干扰少,可用于血液中低浓度苯丙胺类毒品的分析检测。     

Rapid analysis of amphetamines in blood using head space-solid phase microextraction and selected ion monitoring

A simple and rapid method for analysis of methamphetamine (MA) and amphetamine (AP) in blood was developed using head space-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry/electron impact ionization-selected ion monitoring (GC-MS/EI-SIM). A vial containing a blood sample, sodium hydroxide, and pentadeuterated methamphetamine as an internal standard, was heated at 80 °C for 20 min. The extraction fiber of the SPME was exposed for 5 min in the head space of the vial. First, heptafluorobutyric anhydride solution was injected into the injection port of the GC-MS to make heptafluorobutyramide (HFB) derivatives of amphetamines, and compounds absorbed on the fiber were detached by exposing the fiber in the injection port. Straight calibration curves of MA and AP were obtained from 0.01 to 2 μg/g in blood, respectively. No interfering substances were found, and the time for analysis was 30 min for one sample.     

Headspace solid-phase microextraction (HS-SPME) and liquid-liquid extraction (LLE): comparison of the performance in classification of ecstasy tablets. Part 2

Headspace solid-phase microextraction (HS-SPME) is assessed as an alternative to liquid-liquid extraction (LLE) currently used for 3,4-methylenedioxymethampethamine (MDMA) profiling. Both methods were compared evaluating their performance in discriminating and classifying samples. For this purpose 62 different seizures were analysed using both extraction techniques followed by gas chromatography-mass spectroscopy (GC-MS). A previously validated method provided data for HS-SPME, whereas LLE data were collected applying a harmonized methodology developed and used in the European project CHAMP. After suitable pre-treatment, similarities between sample pairs were studied using the Pearson correlation. Both methods enable to distinguish between samples coming from the same pre-tabletting batches and samples coming from different pre-tabletting batches. This finding emphasizes the use of HS-SPME as an effective alternative to LLE, with additional advantages such as sample preparation and a solvent-free process.     

Australian Federal Police seizures of illicit crystalline methamphetamine ('ice') 1998-2002: impurity analysis

Nineteen crystalline methamphetamine ('ice') seizures captured by the Australian Federal Police (AFP) at the Australian border between 1998 and 2002 were analysed. Using a modified gas chromatograph-mass spectrometry (GC-MS) impurity profiling approach of these samples we have identified >30 compounds associated with methamphetamine and/or its synthetic route. Major impurities detected include 1,2-dimethyl-3-phenylaziridine 8, dimethylamphetamine 14, N-formylmethamphetamine 24, N-acetylmethamphetamine 25, 1,3-dimethyl-2-phenylnaphthalene 32, 1-benzyl-3-methylnaphthalene 33 and methamphetamine dimer 34. These data are suggestive of ephedrine/pseudoephedrine as the main precursor of the 'ice' samples seized during 1998-2002. Additionally the two naphthalenes 32 and 33 further identified that 15 items in 9 seizures were produced via the more specific ephedrine/hydriodic acid/red phosphorus method. One sample comprised 75% dimethylamphetamine and 9.7% methamphetamine, representing the first Australian seizure of imported dimethylamphetamine reported.     

Analysis of the impurities in the methamphetamine synthesized by three different methods from ephedrine and pseudoephedrine

Organic impurities of methamphetamine may show different patterns by synthesis. In the present study, we tried to find the impurities reflecting the conditions of synthesis by comparing impurity patterns of the methamphetamine samples synthesized by different methods. Sixteen methamphetamine samples were synthesized from ephedrine and pseudoephedrine by the three different manufacturing methods of Emde, Nagai and Moscow. The synthesized samples were extracted with ethyl acetate containing four internal standards, and the patterns of the organic impurities were investigated by GC-MS and GC-FID . Through the investigation, we found 10 peaks appearing in the latter part of GC chromatograms are characteristic to synthesis. The areas of the selected peaks were converted to the variables suitable for the statistical calculation, and the synthesized samples could be classified into four groups through the resultant cluster analysis.     

Methamphetamine impurity profiling using a 0.32 mm i.d. nonpolar capillary column

Classification of seized methamphetamine by impurity profiling can provide very useful information in criminal investigations of drug traffic routes, sources of supply and relationships between seizures. The aim of this study is to improve and develop an analytical method for detecting impurities such as starting materials and by-products in illegally prepared methamphetamine.HCl samples. A 50mg sample of methamphetamine.HCl was dissolved in 1 ml of buffer solution (four parts 0.1M phosphate buffer pH 7.0 and one part 10% Na2CO3). Impurities were extracted with 0.5 ml of ethyl acetate containing four internal standards (ISs) (n-decane, n-pentadecane, n-nonadecane and n-hexacosane) and analyzed by gas chromatography (GC) using a flame ionization detector (FID) on a DB-5 capillary column (0.32 mmi.d. x 30 m, film thickness 1.0 microm). The use of a middle-bore column offered better separation of the impurity peaks. The correction of the retention times of impurity peaks with four ISs made peak identification very accurate for subsequent data processing. Twenty-four characteristic peaks were selected for comparison and similarity and/or dissimilarity between samples, and the data were evaluated by the Euclidean distance of the relative peak areas after logarithmic transformation. The results indicate that the present method would be useful for methamphetamine impurity profiling.     

Chemical profiling of 3,4-methylenedioxymethamphetamine (MDMA) tablets seized in Hong Kong

During 2000-2001, the Government Laboratory of Hong Kong received over 600,000 ecstasy tablets in more than 2,600 cases. Using GC-MS or FTIR, the major amphetamine-type stimulants were identified, and the samples were categorized into four groups containing: (1) 3,4-methylenedioxymethamphetamine (MDMA), (2) methamphetamine (MA), (3) 3,4-methylenedioxyamphetamine (MDA), or (4) amphetamine. Our study revealed that in Hong Kong MDMA tablets have made up 98 and 71% of the total ecstasy tablets examined in 2000 and 2001, respectively. Among the MDMA cases, 613 cases involving a total of 123,776 tablets in 2001 were randomly selected, and their active ingredients, minor ingredients, and/or impurities were studied using GC-MS and HPLC. Based on the chemical profiles, and irrespective of their different physical characteristics, tablets obtained in different seizures could be determined as to whether or not they could have come from a common origin. The impurities detected in the MDMA tablets also served as excellent chemical markers from which plausible synthetic route(s) of the MDMA were inferred. Our study revealed that 3,4-methylenedioxyphenyl-2-propanone (MDP2P), 3,4-methylenedioxyphenyl-2-propanol (MDP), 3,4-methylenedioxy-N-methylbenzylamine (MDB), piperonal and N-formyl-3,4-methylenedioxymethamphetamine (N-formyl-MDMA) were the most common impurities detected in MDMA tablets seized in Hong Kong. The finding of the phosphate salt of MDMA is intriguing. Based on a presumptive color test, spectroscopic data (FTIR/ESI-MS) and the percentage of MDMA content in a purified phosphate salt of MDMA, the ratio of the phosphate to MDMA was determined to be 1:1, suggesting that the compound is a dihydrogen phosphate salt [i.e. (HMDMA)H2PO4].     

Identification of impurities and statistical classification of methamphetamine tablets (Ya-Ba) seized in Thailand

Impurity profiles of methamphetamine tablets seized in Thailand have been investigated. The samples are extracted with small amounts of ethyl acetate under alkaline condition and the extracts are analyzed by capillary gas chromatography. Nine compounds (1,2-dimethyl-3-phenylaziridine, ephedrine, methylephedrine, N-formylmethamphetamine, N-acetylmethamphetamine, N-formylephedrine, N-acetylephedrine, N,O-diacetylephedrie, methamphetamine dimer) are identified as impurities in methamphetamine tablet. Caffeine and ethyl vanillin are also detected as diluents and/or adulterants, and acetylcodeine monoacetylmorphine and diacetylmorphine are contained in many samples. In addition, trans-3,4-dimethyl-5-phenyl-2-oxazolidone is newly found as an impurity. For characterization and comparison of methamphetamine tablet exhibits, intensely and commonly detectable nine peaks are selected as the factor for multivariate analysis. The procedures reported here permit classification of 250 analyzed exhibits into five groups and characterization of classified groups.     

Miniaturized sample preparation method for determination of amphetamines in urine

A simple and miniaturized sample preparation method for determination of amphetamines in urine was developed using on-column derivatization and gas chromatography-mass spectrometry (GC-MS). Urine was directly applied to the extraction column that was pre-packed with Extrelut and sodium carbonate. Amphetamine (AP) and methamphetamine (MA) in urine were adsorbed on the surface of Extrelut. AP and MA were then converted to a free base and derivatized to N-propoxycarbonyl derivatives using propylchloroformate on the column. Pentadeuterated MA was used as an internal standard. The recoveries of AP and MA from urine were 100 and 102%, respectively. The calibration curves showed linearity in the range of 0.50-50 microg/mL for AP and MA in urine. When urine samples containing two different concentrations (0.50 and 5.0 microg/mL) of AP and MA were determined, the intra-day and inter-day coefficients of variation were 1.4-7.7%. This method was applied to 14 medico-legal cases of MA intoxication. The results were compared and a good agreement was obtained with a HPLC method.     

A contribution to the chemical profiling of 3,4-methylenedioxymethamphetamine (MDMA) tablets

A profiling method for the identification of impurities found in seized 3,4-methylenedioxymethamphetamine (MDMA) tablets is presented. Impurities of interest are extracted from an alkaline solution (pH 12.8) by diethyl ether and submitted to gas chromatography (GC)-mass spectrometry (MS) analyses. Identification of impurities is performed by electron impact ionization (Ei) mass spectrometry and confirmation by positive chemical ionization (Ci+) MS or, when possible, MS/MS (MS(2)). Repeat extractions of the same sample give an average relative standard deviation (R.S.D.) of less than 8% within the same day and 15% between days (results were obtained after normalization by the sum of peak areas, each one being acquired by selected ion monitoring (SIM)). Possible application toward batch comparison of samples is discussed. Chromatographic profiles are compared using the cosine function for evaluating similarity and/or dissimilarity among exhibits.     

The impurity characteristics of methamphetamine synthesized by Emde and Nagai method

Impurity profiling and classification of seized methamphetamine may play an important role in the interpretation of analytical results, the determination of the synthetic method employed, and the criminal investigations of drug traffic routes. Our study is focused on classifying seized methamphetamine samples according to the groups sorted by the types and quantities of impurities present in illicit methamphetamine samples. The samples (100 mg) were dissolved in 2 mL of potassium phosphate buffer (pH 7.0), extracted with 200 μL of ethyl acetate under basic condition, and then analyzed by gas chromatography-mass spectrometry (GC–MS) with a DB-1 capillary column (30 m × 0.25 mm i.d., 0.25 μm). Five impurities are used as criteria for the classification of seized methamphetamine samples by Emde and Nagai method. A total of fifty-two samples of seized methamphetamine were analyzed by GC–MS and classified by five organic impurities, and then sorted into four groups, which are Nagai type, Emde Type, Undetermined I type, and Undetermined II type.