Development of a quick preparation method for the analysis of 11-nor-9-carboxy-∆9-tetrahydrocannabinol in human urine by phenylboronic-acid solid-phase extraction.

A rapid preparation method for the analysis of the urine from a cannabis user was established. Generally, 11-nor-9-carboxy-∆9-tetrahydrocannabinol (THC-COOH), which is one of the main metabolites of ∆9-tetrahydorocannabinol (THC), must be detected from a user's urine to verify cannabis use. However, existing preparation methods are usually multistep and time-consuming processes. Before the analysis by liquid-chromatography tandem mass spectrometry (LC-MS/MS), deconjugation by treatment with ß-glucuronidase or alkaline solution, liquid-liquid extraction or solid-phase extraction (SPE), and evaporation are generally performed. In addition, subsequent derivatization (silylation or methylation) are certainly necessary for gas-chromatography mass spectrometry (GC/MS) analysis. Here, we focused on the phenylboronic-acid (PBA) SPE, which selectively binds compounds with a cis-diol moiety. THC-COOH is metabolized as a glucuronide conjugate (THC-COOGlu) which has cis-diol moieties, therefore, we investigated the conditions of its retention and elution to reduce the operating time. We developed four elution conditions, which afford the following derivatives: acidic elution for THC-COOGlu, alkaline elution for THC-COOH, methanolysis elution for the THC-COOH methyl ester (THC-COOMe), and methanolysis elution and following methyl etherification for O-methyl-THC-COOMe (O-Me-THC-COOMe). All repeatability and recovery rates were evaluated by LC-MS/MS in this study. As a result, these four pathways required short times (within 10-25 min) and exhibited good repeatability and recovery rates. Detection limits of pathway I-IV were 10.8, 1.7, 18.9, and 13.8 ng mL-1, respectively. Lower limits of quantification were 62.5, 31.25, 57.3, and 62.5 ng mL-1, respectively. When proof of cannabis use is required, any elution condition can be selected to match the possessing reference standards and analytical instruments. To our knowledge, this is the first report of using PBA SPE for the preparation of the urine samples containing cannabis and achieving partial derivatization when eluting from a PBA carrier. Our method can provide a new and practical solution for the preparation of the urine samples from cannabis users. Although the PBA SPE method cannot recover THC-COOH in urine because of its lack of a 1,2-diol moiety, this method has technological advantages for simplifying the process and reducing the operating time, thereby avoiding human errors.

Identification and Quantitative Analysis of 2-Fluoromethamphetamine and Its Metabolites in Human Urine.

Various synthetic drugs have appeared over the past years across the world, and phenethylamine derivatives are among them; indeed, aromatic fluoro analogs of methamphetamine and amphetamine have been in the illicit drug market since the early 2000s. Although they are currently widely abused across the world, little information is available on their metabolism and toxicology. Recently, we came across an alleged 2-fluoromethamphetamine (2-FMA) drug abuse case. The urine obtained from the alleged abuser was analyzed as part of a criminal investigation. 2-FMA, 2-fluoroamphetamine (2-FAP) and some related compounds were detected by liquid chromatography-tandem mass spectrometry. In forensic science, both an "unchanged" drug and its metabolite(s) need to be detected in urine to verify the illicit drug use. Notably, the detection of 2-FAP, which is a plausible 2-FMA metabolite, is insufficient as evidence of 2-FMA use because 2-FAP is widely available and may be present as such in taken liquids. In this study, we synthesized analytical standards for N-hydroxy 2-FMA (N-OH-2-FMA) and two diastereomers of 2-fluoroephedrine, which are plausible metabolites of 2-FMA. Using these standards, the urine specimen was found to contain N-OH-2FMA and one diastereomer of 2-fluoroephedrine; moreover, the concentrations of these compounds were successfully determined. The results of our study suggest that N-hydroxylation and aliphatic hydroxylation are the characteristic metabolic pathways of 2-FMA compared with that of methamphetamine. This evidence indicates that both N-OH-2-FMA and 2-fluoroephedrine are plausible candidates as analytical targets for drug-use certification in forensic science.

Mechanically induced single-molecule helicity switching of graphene-nanoribbon-fused helicene on Au(111).

Helicene is a functional material with chirality caused by its characteristic helical geometry. The inversion of its helicity by external stimuli is a challenging task in the advanced control of the molecular chirality. This study fabricated a novel helical molecule, specifically a pentahelicene-analogue twisted aromatic hydrocarbon fused with a graphene nanoribbon, via on-surface synthesis using multiple precursors. Noncontact atomic force microscopy imaging with high spatial resolution confirmed the helicity of the reaction products. The helicity was geometrically converted by pushing a CO-terminated tip into the twisted framework, which is the first demonstration of helicity switching at the single-molecule scale.

Studies on the phase I metabolites of the new designer drug 1-(2,3-dihydro-1H-inden-5-yl)-2-(pyrrolidine-1-yl)butan-1-one (5-PPDI) in human urine.

Pyrrolidinophenones (PPs) are synthetic cathinones containing a pyrrolidine ring that are used recreationally worldwide. Recently, many studies on the metabolism and cytotoxicity of PPs have been published. Here, we focus on new designer drug containing an indan skeleton, 1-(2,3-dihydro-1H-inden-5-yl)-2-(pyrrolidine-1-yl)butan-1-one (5-PPDI), because there have been no reports to date regarding the metabolism of indan-type cathinones. The identification of 5-PPDI phase I metabolites in human urine enables us to determine whether a person has taken 5-PPDI. This metabolite detection approach plays a very important role in the field of forensic science. We synthesized analytical standards of 5-PPDI and four proposed metabolites. A urine sample was prepared by salting-out assisted liquid-liquid extraction with acetonitrile. Analyses of all standards and the urine sample were performed by liquid chromatography high resolution tandem mass spectrometry. As a result, we were able to detect 5-PPDI and its metabolites in the urine specimen. Two diastereomers of synthesized 1-OH metabolites were successfully separated, and only one diastereomer was observed in the urine specimen. To the best of our knowledge, this is the first report on the stereoselective reduction of PPs in humans. Further, we performed quantitative analyses of 5-PPDI and its metabolites in the urine. We identified three characteristic features of 5-PPDI phase I metabolism: (1) hydroxylation at the indan skeleton, (2) stereoselective reduction of the carbonyl group, and (3) hydroxylation of the indan skeleton possibly proceeding more preferentially than any other metabolization. In addition, several structural isomers and diastereomers of 2'-OH metabolites were detected. Based on these data, we propose phase I metabolic pathways of 5-PPDI, which will be essential in understanding the metabolism of other PPs with an indan skeleton.

Quality control of on-surface-synthesised seven-atom wide armchair graphene nanoribbons.

On-surface synthesis is a powerful method for fabricating atomically precise graphene nanoribbons (GNRs), but the products always include defective structures. In this study, scanning tunnelling microscopy and atomic force microscopy were used to determine the length distribution of armchair-edge GNRs with a width of seven carbon atoms (7-AGNRs) synthesised on Au(111) and to characterise defective structures. The product quality was improved by increasing the precursor deposition amount because of a preference for intermolecular polymerisation over intramolecular cyclodehydrogenation at a high coverage. However, the annealing rate had a complex effect on the quality, with a low rate elongating 7-AGNRs but degenerating the length uniformity. These insights advance the understanding of the critical parameters for obtaining high-quality products in high yield by on-surface synthesis.

Differentiation of ring-substituted regioisomers of cathinone analogs by supercritical fluid chromatography.

Various new psychoactive substances, such as cathinone and its analogs, possess similar chemical structures. Accurate identification of structurally similar drugs of abuse is important in forensic drug analysis. Chromatographic differentiation is a powerful analytical technique for this purpose. In this study, we applied supercritical fluid chromatography to differentiate ring-substituted regioisomers of six synthetic cathinone analogs (fluoro-α-pyrrolidinovalerophenone, methyl-α-pyrrolidinovalerophenone, methoxy-α-pyrrolidinovalerophenone, fluoro-α-pyrrolidinooctanophenone, fluoropentedrone, and fluorooctedrone). The examined cathinone analogs were weakly retained on the stationary phase (possessing diol functional group) and eluted quickly. We optimized the conditions to retain the examined cathinone analogs to achieve sufficient separation, and found that the types of functional groups on the stationary phase greatly affected the retention and separation. Systematic examination of the chromatographic conditions showed that the two stationary phases possessing anthracene and pentafluorobenzyl groups had good separation capabilities for the examined 2-, 3-, and 4-regioisomers of six cathinone analogs, which had different skeletal structures. Interestingly, the two stationary phases showed different selectivities, and alteration of the elution order was observed. The developed method was validated and its discrimination ability was investigated by measuring mass spectra and absorption spectra. Supercritical fluid chromatography-ultraviolet absorption spectroscopy/mass spectrometry is a powerful analytical technique for differentiation of ring-substituted cathinone analogs.

Solid-Phase Synthesis of Fluorinated Analogues of Glycosyl 1-Phosphate Repeating Structures from Leishmania using the Phosphoramidite Method.

Bacterial and protozoan sugar chains contain glycosyl 1-phosphate repeating structures; these repeating structures have been studied for vaccine development. The fluorinated analogues of [ß-Gal-(1→4)-α-Man-(1→6)-P-] n , which are glycosyl 1-phosphate repeating structures found in Leishmania, were synthesised using the solid-phase phosphoramidite method. This method has been less extensively studied for the synthesis of glycosyl 1-phosphate units than H-phosphonate chemistry. A stepwise synthesis of a compound containing five such repeating units has been conducted using the phosphoramidite method herein, which is the longest glycosyl 1-phosphate structures to be chemically constructed in a stepwise manner.