Analytical methods for detecting butane, propane, and their metabolites in biological samples: Implications for inhalant abuse detection.

Worldwide, various inhalants are widely abused for recreational purposes, with butane and propane emerging as among the most commonly misused volatile substances, posing a significant risk of sudden death. The rapid elimination and oxidation of these highly volatile compounds upon inhalation necessitate the identification of butane and propane along with their metabolites in biological samples. Hence, the primary objective of this study is twofold: firstly, to establish a method for analyzing butane, propane, and metabolites, and secondly, to demonstrate the detection window and exposure indicators associated with the inhalation of butane and propane. In pursuit of this objective, we developed analytical methods for the determination of isobutane, n-butane, propane, and their nine metabolites in both blood and urine. Headspace-gas chromatography-mass spectrometry (GC-MS) and solid-phase microextraction-GC-MS were employed for the analyses, demonstrating acceptable precision and accuracy. An animal study revealed that isobutane and n-butane were only detectable below the limit of quantification (LOQ) in rat blood 5 min after exposure. Meanwhile, the three major metabolites-2-methyl-2-propanol, 2-butanol, and 2-butanone-were observed 5 min after exposure but persisted in rat urine even 5 h post-exposure. Additionally, human urine samples identified other metabolites, including acetone, acetoin, and 2,3-butanediol isomers. The presence of specific metabolites corresponding to each inhalant confirmed the abuse of butane and propane. This comprehensive approach provides valuable insights into the detection and assessment of inhalation to these volatile substances.

Unilateral versus bilateral Y-type stent-in-stent metal stent insertions in inoperable malignant hilar biliary strictures: A multicenter retrospective study.

BACKGROUND: To date, there is controversy regarding unilateral versus bilateral stent placement in patients with malignant hilar biliary strictures (MHBSs). The aim of this study was to compare the clinical outcomes and complications of unilateral and bilateral (stent-in-stent method) stent placements for these patients. METHODS: We conducted a multicenter retrospective analysis of patients with inoperable MHBS who underwent endoscopic self-expandable metal stent (SEMS) placement from January 2009 to December 2019. Two groups classified according to the stent procedure method were compared for demographic, procedural, and postprocedure factors. Survival analysis for patency loss and overall survival was also conducted. RESULTS: A total of 236 subjects were included. A superior technical success rate was found in the unilateral stent group (98.8% vs. 82.5%, P < 0.001), whereas the clinical success rate was higher in the bilateral group (85.7% vs. 70.5%, P = 0.028). There was no significant difference with respect to complications or patency loss, and the bilateral group had better overall survival (P < 0.01). In the Cox proportional hazard model, MHBSs from lymph node compression were associated with a higher risk of death (HR = 9.803, P = 0.003). In contrast, bilateral SEMS insertion showed reduced postprocedural mortality (HR = 0.316, P = 0.001). CONCLUSIONS: Y-type stent-in-stent bilateral SEMSs are technically difficult but demonstrated more favorable overall survival for palliative bile drainage of inoperable MHBS patients compared to unilateral insertions.

The Use of Endoscopic Clipping in Preventing Delayed Complications after Endoscopic Resection for Superficial Non-Ampullary Duodenal Tumors.

BACKGROUND/AIMS: Endoscopic resection (ER) has recently been accepted as the standard treatment modality for superficial nonampullary duodenal tumors (SNADTs). However, the procedure can cause adverse events such as perforation and bleeding. This study aimed to investigate the efficacy of prophylactic clipping in the prevention of delayed complications. METHODS: A retrospective review of the medical records of patients who underwent ER for SNADT from 3 centers was performed. Patients were divided into 2 groups: the immediate clipping group (ICG) and the no clipping group (NCG). Various baseline characteristics and factors associated with the appearance of delayed complications, such as size of the lesion, tumor location, histologic type, and co-morbidities, were compared between the two groups. RESULTS: A total of 99 lesions from 99 patients were included in this study. Fifty-two patients were allocated into ICG and 47 patients were allocated into NCG. Delayed bleeding occurred in 1 patient from ICG and in 8 patients from NCG. Delayed perforation occurred in 1 patient from ICG and in 3 patients from NCG. There were no procedure-related deaths in both groups. CONCLUSION: Although the use of endoscopic clipping seemed to reduce the risk of developing delayed complications, further studies using a prospective design is required.

Endoscopic Factors that Can Predict Histological Ulcerations in Early Gastric Cancers.

BACKGROUND/AIMS: Predicting histological ulceration in early gastric cancer (EGC) during endoscopic examination is crucial for endoscopists deciding on the treatment modality. The aim of this study was to investigate the endoscopic factors that can predict histological ulcerations in EGCs. METHODS: We retrospectively analyzed patients who underwent endoscopic submucosal dissection (ESD) for EGC. Clinical features and endoscopic characteristics of EGC such as location, histological differentiation, longest diameter, tumor morphology, mucosal break, converging fold, color change, and surface irregularity were reviewed. Histological ulceration was defined based on ESD specimens. RESULTS: A total of 633 EGC lesions from 613 patients were included and histological ulcerations were found in 90 lesions (14.2%). Presence of converging folds, tumor morphology, and color changes on endoscopic examination were related to histological ulceration in the univariate analysis and converging folds along with color changes were statistically significant factors in the multivariate analysis. Kaplan-Meier analysis showed that patients with histological ulcerations in EGCs tended to have higher marginal recurrence rates. CONCLUSION: Mucosal breaks are not equivalent to histological ulcerations. Rather, the existence of converging folds and color changes during endoscopic examination suggest histological ulcerations. Endoscopists should consider these factors when they decide the treatment modality for EGCs.

Concentrations of THC, CBD, and CBN in commercial hemp seeds and hempseed oil sold in Korea.

Hemp seeds and hempseed oil are marketed on- and off-line as health foods and cosmetics and have been reported to have high nutrient contents. However, because of the various side effects of cannabinoids, especially △9-tetrahydrocannabinol (THC), many countries regulate upper limits for THC in products, which creates the need for analytical techniques capable of measuring THC, cannabidiol (CBD), and cannabinol (CBN) levels in commercial hemp seeds and hempseed oil. In the present study, hemp seed and hempseed oil extracts obtained by methanol extraction, were analyzed by gas chromatography-mass spectrometry (GC/MS). Validation of the technique used was performed using calibration curves and by determining LODs, LOQs, specificities, selectivities, and intra- and inter-day precision and accuracies. In addition, matrix effects, process efficiencies, recoveries, and sample stabilities were investigated. In hemp seeds, as determined using the fully optimized method THC concentrations ranged from 0.06 to 5.91 µg/g, CBD concentrations from 0.32 to 25.55 µg/g, and CBN concentrations from 0.01 to 1.50 µg/g; CBN/THC ratios ranged from 0.1 to 1.60, and CBD/THC ratios from 0.11 to 62.56. Furthermore, the (THC + CBN)/CBD ratio of most hemp seed samples was less than one. In hempseed oil, THC concentrations ranged from 0.3 to 19.73 µg/mL, CBD concentrations from 6.66 to 63.40 µg/mL, CBN concentrations from 0.11 to 2.31 µg/mL, CBN/THC ratios from 0.12 to 0.42, and CBD/THC ratios from 3.21 to 22.50. Furthermore, (THC + CBN)/CBD ratios in all hempseed oil samples were less than one. The optimized methanol extraction-GC/MS technique was found to be satisfactory for determining THC, CBD, and CBN concentrations in hemp seeds and hempseed oil.

In Vitro Metabolism of 25B-NBF, 2-(4-Bromo-2,5-Dimethoxyphenyl)-N-(2-Fluorobenzyl)ethanamine, in Human Hepatocytes Using Liquid Chromatography⁻Mass Spectrometry.

25B-NBF, 2-(4-bromo-2,5-dimethoxyphenyl)-N-(2-fluorobenzyl)ethanamine, is a new psychoactive substance classified as a phenethylamine. It is a potent agonist of the 5-hydroxytryptamine receptor, but little is known about its metabolism and elimination properties since it was discovered. To aid 25B-NBF abuse screening, the metabolic characteristics of 25B-NBF were investigated in human hepatocytes and human cDNA-expressed cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT) enzymes using liquid chromatography⁻high resolution mass spectrometry. At a hepatic extraction ratio of 0.80, 25B-NBF was extensively metabolized into 33 metabolites via hydroxylation, O-demethylation, bis-O-demethylation, N-debenzylation, glucuronidation, sulfation, and acetylation after incubation with pooled human hepatocytes. The metabolism of 25B-NBF was catalyzed by CYP1A1, CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2J2, CYP3A4, and UGT2B7 enzymes. Based on these results, it is necessary to develop a bioanalytical method for the determination of not only 25B-NBF but also its metabolites in biological samples for the screening of 25B-NBF abuse.

Determination of boldenone in postmortem specimens including blood and urine samples using LC-MS/MS.

Boldenone (BOLD), one of androgenic anabolic steroids (AAS), although banned in humans, is still available illegally. AAS abuse has previously been associated with various cardiovascular adverse events including acute myocardial infarction, arrhythmia, and sudden death. In this study, the concentration of BOLD was determined in postmortem specimens from the corpse of a human male who intentionally injected BOLD undecylenate into his shoulder muscle. In addition, the endogenous levels of BOLD in the blood and urine samples of young human males have been reported. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with solid-phase extraction (SPE) was developed and validated for the analysis of BOLD in blood, muscular tissue and urine samples. The validation parameters including linearity, accuracy, precision, matrix effect, and recovery were satisfactory. The concentrations of BOLD in the blood of 20 young human males who didn't take BOLD were under the limit of quantitation (LOQ, 0.5 ng/mL). Additionally, the mean level of BOLD in the urine samples was 3.19 ± 1.65 ng/mL (range: 0.37˜6.02 ng/mL). The concentrations of BOLD in the victim's blood from the femoral vein and heart were 140.44 and 25.74 ng/mL, respectively. On the other hand, those in the muscular tissue from the injection site and the urine sample were 142.3 ng/g and 3474 ng/mL, respectively.

Determination of AB-CHMINACA and its metabolites in human hair and their deposition in hair of abusers.

Despite global efforts to control the abuse of synthetic cannabinoids, the high-level of turnover from the market impedes regulation, endangering public health. N-[(1S)-1-(aminocarbonyl)-2-methylpropyl]-1-(cyclohexylmethyl)-1H-indazole-3-carboxamide (AB-CHMINACA) is the most popular synthetic cannabinoid in South Korea since its introduction in 2014. Nonetheless, few studies have been carried out on AB-CHMINACA and its metabolites, and its deposition in human hair. The purpose of this study was to develop and validate an analytical method for detection of AB-CHMINACA and its six metabolites in hair using a liquid chromatography tandem mass spectrometry (LC-MS/MS) system, for forensic applications. The methanol extracts of hair samples were evaporated, filtered, and analyzed by LC-MS/MS with electrospray ionization in positive ion mode. The limits of detection and quantification ranged from 0.5 to 10pg/mg and 2 to 50pg/mg, respectively. Good linearity was achieved within the range of 5-1000pg/mg or 10-1000pg/mg depending on the analyte. Intra- and inter-assay precision and accuracy values were below 15%. No significant variation was observed using different sources of hair matrices. These validation results proved the selectivity, accuracy and reproducibility of the method. The established method was applied to 37 authentic samples from suspected synthetic cannabinoid users. AB-CHMINACA and its two metabolites, AB-CHMINACA M2 and AB-CHMINACA M4, were detected. The concentration of the parent drug was much higher than those of its metabolites, and the amount of AB-CHMINACA M2 was greater than that of AB-CHMINACA M4 in all samples. No other metabolites were detected in the samples.

Development of visual peak selection system based on multi-ISs normalization algorithm to apply to methamphetamine impurity profiling.

The aim of this study is to improve resolution of impurity peaks using a newly devised normalization algorithm for multi-internal standards (ISs) and to describe a visual peak selection system (VPSS) for efficient support of impurity profiling. Drug trafficking routes, location of manufacture, or synthetic route can be identified from impurities in seized drugs. In the analysis of impurities, different chromatogram profiles are obtained from gas chromatography and used to examine similarities between drug samples. The data processing method using relative retention time (RRT) calculated by a single internal standard is not preferred when many internal standards are used and many chromatographic peaks present because of the risk of overlapping between peaks and difficulty in classifying impurities. In this study, impurities in methamphetamine (MA) were extracted by liquid-liquid extraction (LLE) method using ethylacetate containing 4 internal standards and analyzed by gas chromatography-flame ionization detection (GC-FID). The newly developed VPSS consists of an input module, a conversion module, and a detection module. The input module imports chromatograms collected from GC and performs preprocessing, which is converted with a normalization algorithm in the conversion module, and finally the detection module detects the impurities in MA samples using a visualized zoning user interface. The normalization algorithm in the conversion module was used to convert the raw data from GC-FID. The VPSS with the built-in normalization algorithm can effectively detect different impurities in samples even in complex matrices and has high resolution keeping the time sequence of chromatographic peaks the same as that of the RRT method. The system can widen a full range of chromatograms so that the peaks of impurities were better aligned for easy separation and classification. The resolution, accuracy, and speed of impurity profiling showed remarkable improvement.

Estimation of the synthetic routes of seized methamphetamines using GC-MS and multivariate analysis.

One hundred and twenty six seized methamphetamine (MA) samples were analyzed using GC-MS. All the peaks that appeared in the chromatograms were investigated and 61 impurities including n-octacosane (internal standard) were identified. Among them, 37 impurities were already known or newly identified by comparing with commercial library entries and 18 impurities were detected for the first time. To estimate the synthetic routes of MA samples, route specific impurities had to be selected for each method. Two naphthalenes, 1,3-dimethyl-2-phenylnaphthalene and 1-benzyl-3-methylnaphthalene were selected as Nagai route specific impurities and three diasteromers, UK-19.62(58_165_178) I, UK-19.95(58_165_178) II, UK-20.49(58_165_178) III were also selected not only for their high frequency detection only in Nagai samples but also for the high principal component analysis (PCA) correlation values. For the Emde route, N,N-dimethyl-3,4-diphenylhexane-2,5-diamine and N-methyl-1-{4-[2-(methylamino)propyl]phenyl}-1-phenylpropan-2-amine were selected as route specific impurities, and N,N-di(ß-phenylisopropyl)amine I (DPIA I), N,N-di(ß-phenylisopropyl)amine II (DPIA II), N,N-di(ß-phenylisopropyl)methylamine I (DPIMA I) and N,N-di(ß-phenylisopropyl)methylamine II (DPIMA II) were selected for the Leuckart route. With these route specific impurities, synthetic routes could be identified for 78 of the 126 samples. The 61 impurities were registered in AMDIS target component library and the GC-MS data were deconvoluted. After AMDIS deconvolution, a matrix file was composed and then multivariate analyses were performed to estimate the synthetic route for unknown samples. The unsupervised methods, hierarchical clustering analysis (HCA) and PCA clustered the samples according to the closeness between samples. Two classification functions were obtained from discriminant analysis (DA) and the synthetic routes of the unknown samples were predicted using these two functions.

Determination of XLR-11 and its metabolites in hair by liquid chromatography-tandem mass spectrometry.

Analysis of drugs in hair is often used as a routine method to obtain detailed information about drug ingestion. However, few studies have been conducted on disposition of synthetic cannabinoids including cyclopropylindoles (UR-144 and XLR-11) and their metabolites in hair. XLR-11 has been widely abused in South Korea recently. Identification of metabolites in hair can be an important proof of synthetic cannabinoids use because it can exclude the possibility of passive smoke exposure. In this study, we described a quantitative analytical method of XLR-11 and its metabolites (UR-144, UR-144 N-5-hydroxypentyl metabolite, UR-144 N-4-hydroxypentyl metabolite, UR-144 N-pentanoic acid metabolite and XLR-11 N-4-hydroxypentyl metabolite) in hair by liquid chromatography with ESI-MS/MS. The target analytes were extracted with methanol from washed and cut hair samples and the extracts were evaporated, filtered and analyzed by LC-MS/MS with electrospray ion source in positive-ionization mode. JWH-018-d9 and JWH-018 N-5-hydroxypentyl metabolite-d5 were used as internal standards. Chromatographic separation was completed within 15 min. No interferences were detected in 10 blank hair samples. In intra- and inter-assay precision and accuracy study, CV (%) and bias (%) were below 12. The limit of detection (LOD) was 0.1∼2 pg/mg and the limit of quantification (LOQ) was 0.2-2 pg/mg, respectively. The validation results proved that the method was selective, accurate and precise with acceptable linearity within calibration range. No significant variation was observed by different sources of matrices. This method was applied to hair samples from 14 individual suspects of XLR-11 use. In this result, XLR-11, UR-144, UR-144 N-5-hydroxypentyl metabolite and UR-144 N-pentanoic acid metabolite, XLR-11 N-4-hydroxypentyl metabolite were detected. The concentration of XLR-11 as a parent drug was much higher than other metabolites. UR-144 N-5-hydroxy metabolite and UR-144 N-pentanoic acid were detected mainly in the authentic hair samples from suspected of XLR-11 use. UR-144 N-4- hydroxypentyl metabolite was not detected in all cases.

Impact of ABO Incompatibility on the Development of Acute Antibody-Mediated Rejection in Kidney Transplant Recipients Presensitized to HLA.

Whether the coexistence of anti-A/B antibody and donor specific anti-HLA antibody (HLA-DSA) has a synergistic impact on the development of acute antibody-mediated rejection (AAMR) in kidney transplant recipients (KTRs) is unclear. This study includes 92 KTRs who received a kidney from an ABO-incompatible (ABOi) donor or were presensitized to donor HLA (HLAs) and 292 controls (CONT). HLAs was defined as a crossmatch positivity or the presence of HLA-DSA. We compared the incidence of AAMR among ABOi (n = 58), ABOi+HLAs (n = 12), HLAs (n = 22), and CONT (n = 292) groups and evaluated the risk factors and antibody type (anti-A/B vs. HLA-DSA) responsible for AAMR. AAMR developed less frequently in ABOi and CONT than in the ABOi+HLAs or HLAs (P < 0.05 for all); however, there was no difference between the ABOi+HLAs and HLAs groups. AAMR developed more frequently with strong HLA-DSA at baseline; however, high baseline anti-A/B titer did not affect AAMR development. Strong baseline HLA-DSA was an independent predictor for AAMR, however the baseline anti-A/B titer was not. All four AAMR episodes in ABOi+HLAs were positive to HLA-DSA but not to anti-A/B. In conclusion, ABO incompatibility does not increase the risk for AAMR in HLAs KTRs.

Determination of major metabolites of MAM-2201 and JWH-122 in in vitro and in vivo studies to distinguish their intake.

Abuse of fluorinated synthetic cannabinoid analogs to avoid existing legal regulations has increased globally. The fluorinated JWH-122 analog, MAM-2201, was first reported in September 2012 as an ingredient in herbal mixtures in Korea. MAM-2201 is more potent than JWH-122 and a fatal intoxication case has been reported. In this study, we identified major MAM-2201 and JWH-122 metabolites from in vitro metabolism studies using human liver microsomes and compared the results with those of urine specimens from suspected MAM-2201 or JWH-122 users. MAM-2201 and JWH-122 produced common metabolites, N-5-hydroxylated, N-4-hydroxylated and carboxylated JWH-122 metabolites. Trace amounts of an N-4-hydroxylated MAM-2201 metabolite, a characteristic MAM-2201 metabolite, was detected in only a few urine specimens from MAM-2201 users. Both in vitro and in vivo studies demonstrated that N-5-hydroxylated JWH-122 metabolite was the primary metabolite of MAM-2201, whereas N-4-hydroxylated JWH-122 metabolite was predominant in JWH-122 metabolism. Based on these results, relative concentrations of N-5- and N-4-hydroxylated JWH-122 metabolites should be considered to verify MAM-2201 or JWH-122 users.

Analysis of pharmaceutical impurities in the methamphetamine crystals seized for drug trafficking in Korea.

Some methamphetamine (MA) crystals contain pharmaceutical impurities. They often come from the co-ingredients of cold drugs used for extracting ephedrine or pseudoephedrine. Though these impurities are not so commonly encountered, they reflect the trends in precursor chemicals and manufacturing sources. As a result of monitoring impurities in the MA crystals seized in Korea during 2006-2011, 10 species of pharmaceutical impurities were identified by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. They may be co-ingredients of the legal drugs used as a source of ephedrine or pseudoephedrine. In contrast, some of them are presumed to be adulterants added during or after clandestine synthesis. It is interesting that some of these have been identified in the MA crystals seized in other countries in the same year. Species of pharmaceutical impurities in the MA crystals increased particularly in 2010, indicating a change in precursor chemicals and/or manufacturing sources.

Simultaneous analysis of synthetic cannabinoids in the materials seized during drug trafficking using GC-MS.

A rapid and simple gas chromatography-mass spectrometry (GC-MS) method was developed and validated to identify and quantify synthetic cannabinoids in the materials seized during drug trafficking. Accuracy and reproducibility of the method were improved by using deuterated JWH-018 and JWH-073 as internal standards. Validation results of the GC-MS method showed that it was suitable for simultaneous qualitative and quantitative analyses of synthetic cannabinoids, and we analyzed synthetic cannabinoids in seized materials using the validated GC-MS method. As a result of the analysis, ten species of synthetic cannabinoids were identified in dried leaves (n = 40), bulk powders (n = 6), and tablets (n = 14) seized in Korea during 2009-2012, as a single ingredient or as a mixture with other active co-ingredients. JWH-018 and JWH-073 were the most frequently identified compounds in the seized materials. Synthetic cannabinoids in the dried leaves showed broad concentration ranges, which may cause unexpected toxicity to abusers. The bulk powders were considered as raw materials used to prepare legal highs, and they contained single ingredient of JWH-073, JWH-019, or JWH-250 with the purity over 70 %. In contrast, JWH-018 and JWH-073 contents in the tablets were 7.1-13.8 and 3.0-10.2 mg/g, respectively. Relatively low contents in the tablets suggest that the synthetic cannabinoids may have been added to the tablets as supplements to other active co-ingredients.

Development of an automated data processing method for sample to sample comparison of seized methamphetamines.

The information about the sources of supply, trafficking routes, distribution patterns and conspiracy links can be obtained from methamphetamine profiling. The precursor and synthetic method for the clandestine manufacture can be estimated from the analysis of minor impurities contained in methamphetamine. Also, the similarity between samples can be evaluated using the peaks that appear in chromatograms. In South Korea, methamphetamine was the most popular drug but the total seized amount of methamphetamine whole through the country was very small. Therefore, it would be more important to find the links between samples than the other uses of methamphetamine profiling. Many Asian countries including Japan and South Korea have been using the method developed by National Research Institute of Police Science of Japan. The method used gas chromatography-flame ionization detector (GC-FID), DB-5 column and four internal standards. It was developed to increase the amount of impurities and minimize the amount of methamphetamine. After GC-FID analysis, the raw data have to be processed. The data processing steps are very complex and require a lot of time and effort. In this study, Microsoft Visual Basic Application (VBA) modules were developed to handle these data processing steps. This module collected the results from the data into an Excel file and then corrected the retention time shift and response deviation generated from the sample preparation and instruments analysis. The developed modules were tested for their performance using 10 samples from 5 different cases. The processed results were analyzed with Pearson correlation coefficient for similarity assessment and the correlation coefficient of the two samples from the same case was more than 0.99. When the modules were applied to 131 seized methamphetamine samples, four samples from two different cases were found to have the common origin and the chromatograms of the four samples were appeared visually identical. The developed VBA modules could process raw data of GC-FID very quickly and easily. Also, they could assess the similarity between samples by peak pattern recognition using whole peaks without spectral identification of each peak that appeared in the chromatogram. The results collectively suggest that the modules would be useful tools to augment similarity assessment between seized methamphetamine samples.

Cross-examination of liquid-liquid extraction (LLE) and solid-phase microextraction (SPME) methods for impurity profiling of methamphetamine.

Impurities in 48 methamphetamine (MA) samples were analyzed by liquid-liquid extraction (LLE) and headspace solid-phase microextraction (HS-SPME) methods. MPS-2 autosampler was used to improve reproducibility of SPME method, and nonadecane (C(19)) diluted with potassium bromide (KBr) powder was used as an internal standard for standardizing retention time. Impurities identified by SPME method showed different patterns compared with LLE method. Non-volatile impurities like methamphetamine dimer were not identified by SPME method, but some volatile impurities like diphenylketone, caprolactam and lots of unknowns were identified only by SPME method. 1-Phenyl-2-propanone (P2P), 1-phenyl-2-propanol and benzylcyanide peaks could be discriminated clearly by SPME method without interference of amphetamine, an artifact originates from MA degradation. Differences in the impurity patterns resulted in different clustering results. When 48 MA samples were classified into 5 LLE and 5 SPME clusters, cross-matching of the clusters resulted in 8 sub-clusters. It shows that combination of the different extraction methods can distinguish the differences which cannot be distinguished by LLE or SPME method alone, and can improve reliability of the profiling results.

The study of metabolite-to-parent drug ratios of methamphetamine and methylenedioxymethamphetamine in hair.

The metabolite-to-parent drug ratios were determined in the hair of 2444 methamphetamine (MA) abusers who had produced MA-positive hair results from 2001 to May 2005 and in the hair of 53 ecstasy abusers who had produced positive methylenedioxymethamphetamine (MDMA) hair results from 2002 to May 2005. For the hair analyses, hair strands were washed, cut into small pieces and extracted for 20 h in 1 mL methanol containing 1% HCl. Drugs in the extract were determined by gas chromatography-mass spectrometry (GC-MS) using selective ion monitoring after derivatization with trifluoroacetic anhydride. The six range groups were divided as follows on the basis of MA concentrations in hair (n = 2389): 0.5-5 ng/mg (n = 950), 5-10 ng/mg (n = 582), 10-20 ng/mg (n = 503), 20-30 ng/mg (n = 160), 30-40 ng/mg (n = 80), more than 40 ng/mg (n = 114) to assess the correlations between MA concentrations and metabolite-to-parent drug ratios. In groups of higher MA concentrations, lower ratios of AP/MA were found, and there was a statistically significant difference among six range groups. Comparisons of age groups (tens, twenties, thirties, forties, fifties, and sixties) and male and female subjects for the ratios of AP/MA showed a statistically significant difference. The detection of metabolites and the parent drug with reasonable ratios was found to be a useful indicator for distinguishing internal drug incorporation from external contamination. In our study, MA users can produce 0.4-116% (mean = 9%) of amphetamine (AP) concentrations in hair, and ecstasy users 1-110% (mean = 12%) of methylenedioxyamphetamine (MDA) in appropriately washed hair samples.

The prevalence of MDMA/MDA in both hair and urine in drug users.

The prevalence and age distribution of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) in hair samples by gas chromatography/mass spectrometry (GC/MS) were studied. The recoveries obtained from hair were 97% and 99% for MDMA and MDA, respectively. The inter- and intra-assay precision and accuracy were determined. Out of 791 hair samples, 44 (5.6 %) contained MDMA and/or MDA. Out of these 44 subjects, urinalyses from 35 were negative for both MDMA and MDA, while only 9 were positive. We also evaluated concentrations of MDMA and MDA, and the metabolite-to-parent drug ratios. This study showed that the abuse of MDMA or MDA was found principally among young adults and male abusers. We found the epidemiology of ecstasy users in Korea between March 2002 and April 2003.

Correlation of methamphetamine results and concentrations between head, axillary, and pubic hair.

This study was designed to compare the qualitative results and concentrations of methamphetamine (MA) and its metabolite amphetamine (AP) in head hair and hair collected from different parts of the body (axillae and pubis). Hair from subjects (N = 14) suspected MA users was simultaneously collected. Hair preparation involved washing step, fine cutting, overnight extraction, derivatization by the trifluoroacetic anhydride, and gas chromatography/mass spectrometry (GC/MS) using selective ion monitoring. In this study, we found a good correlation of the qualitative results for MA between head hair and hair on other parts of the body, but there were some differences in concentrations of MA and AP. Namely, the concentrations of MA and AP were higher in axillary and pubic hair than in head hair.