Separation of isotopologues of amphetamine with various degree of deuteration on achiral and polysaccharide-based chiral columns in high-performance liquid chromatography.

Hydrogen/deuterium (H/D) isotope effects are not unusual in chromatography and such phenomena have been observed in both gas- and liquid-phase separations. Despite the numerous reports on this topic, the understanding of mechanisms and the underlying noncovalent interactions at play remains rather challenging. In our recent study, we reported baseline separation of isotopologoues of some amphetamine (AMP) derivatives on achiral and polysaccharide-based chiral columns, as well as some correlations between the degree of separation of enantiomers and isotopologues on (the same) polysaccharide-based chiral column(s). Following our previous findings on isotope effects in high-performance liquid chromatography, we report herein a comparative study on the isotope effects observed with AMP and methamphetamine (MET). The impact of some pivotal factors such as the number of deuterium atoms part of AMP isotopologues, the structure of its isotopomers, the chemical structure of the achiral and chiral stationary phases used in this study, and the use of methanol- vs acetonitrile-containing mobile phases on the isotope effects was examined and discussed. Quantitative correlations between the observed isotope effects and the enantioselectivity of the chiral columns used are also shortly discussed. Furthermore, considering the chromatographic results as benchmark experimental data, we attempted to elucidate the molecular bases of the observed phenomena using quantum mechanics calculations.

[NMR Study of the Discrimination of Enantiomers of Methamphetamine and Its Raw Materials Using Chiral Solvating Agents].

Some controlled substances, such as stimulants and narcotics, have asymmetric carbons in their molecules. Because the enantiomers do not always show the same pharmacological effects, and there are substances with different controls due to differences in their stereochemistry, a simple and unambiguous method for assessment of the composition of enantiomers is necessary. In this study, to develop a simple and rapid stereoscopic identification method for methamphetamine and its raw materials (ephedrine and pseudoephedrine), the 1H-NMR method was studied using three commercially available chiral solvating agents (CSAs); 1,1'-bi(2-naphthol)(BINOL), 2,2,2-trifluoro-1-(9-anthryl)ethanol (TFAE) and α-methoxy-α-(trifluoromethyl)phenylacetic acid (MTPA). In addition, the accuracy of the optical purity, which was measured using samples mixed with enantiomers in various ratios, was investigated. The NMR peaks of the enantiomers were separated by adding (R)- or (S)-form of BINOL, TFAE or MTPA to the chloroform-d solution of methamphetamine, ephedrine or pseudoephedrine. A sufficient discrimination of enantiomers was obtained by adding about 10 equal amounts of each CSA to the solutions. With regard to the optical purity, it was possible to determine accurately the mixing of small amounts of enantiomers of about 5% even if the NMR peaks did not reach the baseline separation, when impurity peaks do not overlap. This method will be one of the useful techniques for the rapid and simple discrimination of enantiomers of illegal methamphetamine and its raw materials.

Polyoxometalate-Based Frameworks as Adsorbents for Drug of Abuse Extraction from Hair Samples.

The linkage of molecular components into functional heterogeneous framework materials has revolutionized modern materials chemistry. Here, we use this principle to design polyoxometalate-based frameworks as high affinity adsorbents for drugs of abuse, leading to their application in solid-phase extraction analysis. The frameworks are assembled by the reaction of a Keggin-type polyanion, [SiW12O40]4-, with lanthanoids Dy(III), La(III), Nd(III), and Sm(III) and the multidentate linking ligand 1,10-phenanthroline-2,9-dicarboxylic acid (H2PDA). Their reaction leads to the formation of crystalline 1D coordination polymers. Because of the charge mismatch between the lanthanoids (+3) and the dodecasilicotungstate (-4), we observe incorporation of the PDA2- ligands into crystalline materials, leading to four polyoxometalate-based frameworks where Keggin-type heteropolyanions are linked by cationic {Lnn(PDA)n} groups (Ln = Dy (1), La (2), Nd (3), and Sm (4)). Structural analysis of the polyoxometalate-based frameworks suggested that they might be suitable for surface binding of common drugs of abuse via supramolecular interactions. To this end, they were used for the extraction and quantitative determination of four model drugs of abuse (amphetamine, methamphetamine, codeine, and morphine) by using micro-solid-phase extraction (D-µSPE) and high-performance liquid chromatography (HPLC). The method showed wide linear ranges, low limits of detection (0.1-0.3 ng mL-1), high precision, and satisfactory spiked recoveries. Our results demonstrate that polyoxometalate-based frameworks are suitable sorbents in D-µSPE for molecules containing amine functionalities. The modular design of these networks could in the future be used to expand and tune their substrate binding behavior.

Addressing the instability issue of dopamine during microdialysis: the determination of dopamine, serotonin, methamphetamine and its metabolites in rat brain.

Dopamine is a catecholamine neurotransmitter that degrades rapidly in aqueous solutions; hence, its analysis following brain microdialysis is challenging. The aim of the current study was to develop and validate a new microdialysis coupled LC-MS/MS system with improved accuracy, precision, simplicity and turnaround time for dopamine, serotonin, methamphetamine, amphetamine, 4-hydroxymethamphetamine and 4-hydroxyamphetamine analysis in the brain. Dopamine degradation was studied with different stabilizing agents under different storage conditions. The modified microdialysis system was tested in vitro, and was optimized for best probe recovery, assessed by %gain. LC-MS/MS assay was developed and validated for the targeted compounds. Stabilizing agents (ascorbic acid, EDTA and acetic acid) as well as internal and cold standards were added on-line to the dialysate flow. Assay linearity range was 0.01-100 ng/mL, precision and accuracy passed criteria, and LOQ and LLOQ were 0.2 and 1.0 pg, respectively. The new microdialysis coupled LC-MS/MS system was used in Wistar rats striatum after 4 mg/kg subcutaneous methamphetamine. Methamphetamine rapidly distributed to rat striatum reaching an average ~200 ng/mL maximum, ~82.5 min post-dose. Amphetamine, followed by 4-hydroxymethamphetamine, was the most abundant metabolite. Dopamine was released following methamphetamine injection, while serotonin was not altered. In conclusion, we proposed and tested an innovative and simplified solution to improve stability, accuracy and turnover time to monitor unstable molecules, such as dopamine, by microdialysis.

Development of a Pencil Drawn Paper-based Analytical Device to Detect Lysergic Acid Diethylamide (LSD)*, †.

The need for agile and proper identification of drugs of abuse has encouraged the scientific community to improve and to develop new methodologies. The drug lysergic acid diethylamide (LSD) is still widely used due to its hallucinogenic effects. The use of voltammetric methods to analyze narcotics has increased in recent years, and the possibility of miniaturizing the electrochemical equipment allows these methods to be applied outside the laboratory; for example, in crime scenes. In addition to portability, the search for affordable and sustainable materials for use in electroanalytical research has grown in recent decades. In this context, employing paper substrate, graphite pencil, and silver paint to construct paper-based electrodes is a great alternative. Here, a paper-based device comprising three electrodes was drawn on 300 g/m2 watercolor paper with 8B pencils, and its efficiency was compared to the efficiency of a commercially available screen-printed carbon electrode. Square wave voltammetry was used for LSD analysis in aqueous medium containing 0.05 mol/L LiClO4 . The limits of detection and quantification were 0.38 and 1.27 µmol/L, respectively. Both electrodes exhibited a similar voltammetric response, which was also confirmed during analysis of a seized LSD sample, with recovery of less than 10%. The seized samples were previously analyzed by GCMS technique, employing the full scan spectra against the software spectral library. The electrode selectivity was also tested against 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine. It was possible to differentiate these compounds from LSD, indicating that the developed paper-based device has potential application in forensic chemistry analyses.

A systematic investigation of forensic hair decontamination procedures and their limitations.

The effectiveness of decontamination procedures used for the removal of external drug contamination in forensic hair analysis is an ongoing debate. This investigation evaluated wash methods complying with Society of Hair Testing (SoHT) guidelines and their capacity to remove cocaine (COC) and methamphetamine (MA) from artificially contaminated hair. The most effective decontamination method was determined using a systematic approach, involving (1) an initial washing solvent screen, (2) optimization of wash duration, (3) comparison of sequential wash methods, and (4) reanalysis of clinical hair samples. For analysis, hair was subjected to micro-pulverized methanolic extraction prior to quantitation by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Methanol (MeOH) and 0.1 M phosphate buffer (pH 6) were the most effective organic and aqueous solvents, respectively, removing 28%-38% of COC and 16%-31% of MA. Wash durations longer than 30-60 minutes did not remove additional amounts, and a more efficient sequential wash method was subsequently developed. Despite this, the interpretation of reportable results relative to the SoHT cut-off levels was unchanged for most clinical hair samples reanalyzed after washing by agitation for 30 minutes with MeOH. These findings highlight the inability of decontamination solvents to completely remove external COC and MA contamination from hair, including wash methods adhering to SoHT guidelines.

Multi-residue method for enantioseparation of psychoactive substances and beta blockers by gas chromatography-mass spectrometry.

Currently, consumption of illicit drugs and pharmaceuticals has increased significantly. Many of these substances are chiral and can be available as racemates or enantiomerically pure. Determination of the enantiomeric fraction (EF) in wastewater is useful for: i) distinguishing between the consumption of prescribed and illicit drugs; ii) identification of possible local of illegal synthesis; iii) illegal discharge of sewage and estimation of illicit drugs and pharmaceuticals consumption by a community (wastewater-based epidemiology). This work describes the development of an indirect method by gas chromatography-mass spectrometry (GC-MS) for enantiomeric quantification of chiral substances namely psychoactive drugs and ß-blockers based on the formation of diastereomers using (R)-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride ((R)-MTPA-Cl) as chiral derivatization reagent. The developed method presented linearity (R2 > 0.99) for 20 compounds, 9 diastereomer pairs and paroxetine (PAR) and sertraline (SER). Recovery ranged from 80.7 to 114.5% (RSD < 9.1%) and accuracy between 84.6 and 118% (RSD < 9.9%). The limits of detection (LOD) varied from 0.03 and 26.0 ngL-1 and limits of quantification (LOQ) from 0.15 and 104 ngL-1. Results showed the occurrence of amphetamine (AMP), illicit drugs as 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (MAMP), alprenolol (ALP), norfluoxetine (NFLX), (SER), metoprolol (MET) and propranolol (PHO) at concentrations ranging from 21.7 ngL-1 (MDMA) to 622 ngL-1 (PHO). Measured concentrations were used to estimate the drug loads of the target chiral substances in a specific population. The EF was determined providing valuable information about the consumption and origin of the target drugs.

Hybrid Solid-Phase Extraction for Selective Determination of Methamphetamine and Amphetamine in Dyed Hair by Using Gas Chromatography-Mass Spectrometry.

Sample preparation is an important step in the isolation of target compounds from complex matrices to perform their reliable and accurate analysis. Hair samples are commonly pulverized or processed as fine cut, depending on preference, before extraction by techniques such as solid-phase extraction (SPE), liquid-liquid extraction, and other methods. In this study, a method based on hybrid solid-phase extraction (hybridSPE) and gas chromatography-mass spectrometry (GC-MS) was developed and validated for the determination of methamphetamine (MA) and amphetamine (AP) in hair. The hair samples were mechanically pulverized after washing with de-ionized water and acetone. The samples were then sonicated in methanol at 50 °C for 1 h and centrifuged at 50,000× g for 3 min. The supernatants were transferred onto the hybridSPE cartridge and extracted using 1 mL of 0.05 M methanolic hydrogen chloride. The combined solutions were evaporated to dryness, derivatized using pentafluoropropionic anhydride, and analyzed by GC-MS. Excellent linearity (R2 > 0.9998) was achieved in the ranges of 0.05-5.0 ng/mg for AP and 0.1-10.0 ng/mg for MA. The recovery was 83.4-96.8%. The intra- and inter-day accuracies were -9.4% to 5.5% and -5.1% to 3.1%, while the intra- and inter-day precisions were within 8.3% and 6.7%, respectively. The limits of detections were 0.016 ng/mg for AP and 0.031 ng/mg for MA. The validated hybridSPE method was applied to dyed hair for MA and AP extraction and compared to a methanol extraction method currently being used in our laboratory. The results showed that an additional hybridSPE step improved the recovery by 5.7% for low-concentration quality control (QC) samples and by 24.1% for high-concentration QC samples. Additionally, the hybridSPE method was compared to polymeric reversed-phase SPE methods, and the absolute recoveries for hybridSPE were 50% and 20% greater for AP (1.5 ng/mg) and MA (3.0 ng/mg), respectively. In short, the hybridSPE technique was shown to minimize the matrix effects, improving GC-MS analysis of hair. Based on the results, the proposed method proved to be effective for the selective determination of MA and AP in hair samples.

Developed nano carbon-based coating for simultaneous extraction of potent central nervous system stimulants from urine media by stir bar sorptive extraction method coupled to high performance liquid chromatography.

A nano graphene oxide sol-gel composite (NGO/sol-gel) applied as a coating of a capillary glass tube stir bar to develop a novel stir bar sorptive extraction (SBSE) method for simultaneous extraction of amphetamine (AMP) and methamphetamine (MET) from biological urine sample. Lab-synthesized NGO was applied with methyltrimethoxysilane (MTMOS) and Tetraethoxysilane (TEOS) as sol-gel precursor. NGO/sol-gel was deposited on the surface of a capillary glass tube to prepare stir bar sorptive extraction adsorbent by a simple and fast method. The scanning electron micrograph images showed a three dimensional structure of lab-made device suitable for SBSE method for simultaneous extraction of AMP and MET. Effective extraction parameters were investigated. Through studied suitable extraction conditions, satisfactory linearity was achieved in the concentration range of 50-2000 ngmL-1 for AMP and 40-2500 ngmL-1 for MET. The relative recovery of the analytes were 99.5 and 99.7% for AMP and MET, respectively for positive urine samples were studied by novel introduced method. The results cleared that NGO/sol-gel composite could be used as practical method in laboratories as an efficient SBSE adsorbent for drugs determination in urine matrix.

Lab-made solid phase microextraction phases for off line extraction and direct mass spectrometry analysis: Evaluating the extraction parameters.

The analyses of drugs and metabolites in complex matrices have been widely studied in recent years. However, due to high levels endogenous compounds and matrix complexity, these analyses require a sample pre-treatment step. To this aim, two lab-made extractive phases were integrated to probe electrospray ionization mass spectrometry (PESI-MS) technique for direct analysis of illicit drugs in biological fluids and phorbol esters in Jatropha curcas extract. The polypyrrole (PPy) phase was electropolymerized onto a platinum wire surface by cyclic voltammetry. The molecularly imprinted polymer (MIP) was synthesized and adhered onto a stainless-steel needle with epoxy resin. The PPy-PESI-MS method showed to be linear in a concentration range from 1 to 500 µg L-1, with accuracy values between -2.1 and 14%, and precision values between 0.8 and 10.8%. The MIP-PESI-MS method showed to be linear in a concentration range from 0.9 to 30 mg L-1, with accuracy values between -1.6 and -15.3%, and precision values between 4.1 and 13.5%.

Epoxide-derived mixed-mode chromatographic stationary phases for separation of active substances in fixed-dose combination drugs.

A method for the preparation of novel mixed-mode reversed-phase/strong cation exchange stationary phase for the separation of fixed-dose combination drugs has been developed. An epoxysilane bonded silica prepared by vapor phase deposition was used as a starting material to produce diol, octadecyl, sulfonate, and mixed octadecyl/sulfonate groups bonded silica phases. The chemical structure and surface coverage of the functional groups on these synthesized phases were confirmed by fourier-transform infrared and solid-state 13 C NMR spectroscopy and elemental analysis. Alkylbenzene homologs, basic drugs, nucleobases and alkylaniline homologs were used as probes to demonstrate the reversed-phase, ion exchange, hydrophilic interaction and mixed-mode retention behaviors of these stationary phases. The octadecyl/sulfonate bonded silica exhibits pronounced mixed-mode retention behavior and superior retentivity and selectivity for alkylaniline homologs. The mixed-mode retention is affected by either ionic or solvent strength in the mobile phase, permiting optimization of a separation by fine tuning these parameters. The mixed-mode stationary phase was applied to separate two fixed-dose combination drugs: compound reserpine tablets and compound methoxyphenamine capsules. The results show that simultaneous separation of multiple substances in the compound dosage can be achieved on the mixed-mode phase, which makes multi-cycles of analysis for multiple components obsolete.

Metal organic framework based carbon porous as an efficient dispersive solid phase extraction adsorbent for analysis of methamphetamine from urine matrix.

Carboxylated carbon porous adsorbent was derived from zeolite imidazole framework (ZIF-8) via carbonization of ZIF-8 under a nitrogen atmosphere. The synthesized carboxylated adsorbent was fully characterized by various techniques including Fourier transform spectroscopy (FTIR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and zeta potential analysis. The carboxylated adsorbent was applied as dispersive solid phase extraction (DSPE) adsorbent for efficient extraction of methamphetamine (MET) from biological urine samples. Several extraction parameters influencing the extraction efficiency were investigated and the calibration curve was plotted under optimized conditions in urine media. The method showed a good linearity in the range of 50-2500 ng/mL. The limit of detection (LOD) and limit of quantification (LOQ) was 10 and 35.80 ng/mL, respectively. A satisfactory analysis of the positive real samples with the recovery of 99.83% confirms the applicability of the proposed method in different clinical and forensic laboratories.

Postmortem analysis of famprofazone and its metabolites, methamphetamine and amphetamine, in porcine bone marrow.

Forensic toxicologists typically work with body fluids, such as blood and urine, or visceral tissues. The analysis of alternative samples, such as bone marrow, can be requested when the commonly used samples are unavailable due to an extended time lapse between the time of death and collection of the material to be analysed. In this study, a method for the analysis of the lipophilic drug famprofazone (FA) and its metabolites, methamphetamine (MA) and amphetamine (AM), in bone marrow was developed, validated and applied to bone marrow from pigs given controlled doses of famprofazone. This method involves enzymatic bone-cleaning, fragmentation of the bones with the assistance of a micro electric motor, optimization of clean-up and LLE (liquid/liquid extraction) conditions and determination by GC/MS. After evaluation through statistical tests, such as Shapiro Wilk for normality and Cochran for homoscedasticity, a linear model was applied in the range of 100 (LOQ) - 2000 ng g-1. Inter-day precision and bias was always < 4.6%. In real sample analysis, bone marrow FA and MA concentrations ranged from 103 to 232 and from 174 to 267 ng g-1, respectively; AM was not detected. The obtained results are useful for application in forensic toxicological protocols (human autopsy cases) and as a starting point for the development of further analytical tools.

Emulsification microextraction of amphetamine and methamphetamine in complex matrices using an up-to-date generation of eco-friendly and relatively hydrophobic deep eutectic solvent.

In this study, a new extraction medium based on a quite bio-compatible and bio-degradable deep eutectic solvent comprising choline chloride and phenylethanol (ChCl: Ph-ETOH) was simply and cheaply synthesized at room temperature. At the next step, it was effectively utilized at the service of air agitated-emulsification microextraction (AA-EME) of two major amphetamine-type stimulants (ATSs) in human plasma and pharmaceutical wastewater pursued by high performance liquid chromatography-ultraviolet detection (HPLC-UV). This safe, effective, and rapid enrichment process based on the new low-density DES was easily practicable via a homemade extraction cell possessing a narrow neck and with no extra demand the emulsifier intermediates. Statistical study of main parameters effects using central composite design (CCD) combined with desirability function (DF) demonstrated that pH 12, 250 µL of extraction solvent, 8 air agitation cycles, and 5% of salt amount resulted in maximum extraction efficiencies (63-66%) with DF value close to 0.98. Under optimal conditions, wide linear dynamic ranges (LDRs) of 15.0-2000 and 8.0-3000 ng mL-1 with the determination coefficients (R2s) close to 0.99 were obtainable for amphetamine and methamphetamine, respectively. Low limits of detection (LODs) as well as relative standard deviations (%RSDs, n = 3) were found to be 2.0-5.0 ng mL-1 and 5.7-7.8%, respectively. Also, enrichment factors (EFs) were quantitative in the span of 47-50. On the other hand, satisfactory and accurate assessment at low levels close to therapeutic and toxic domains in human plasma sample and pharmaceutical wastewater was successfully obtained.

Resolution of methoxyphenamine and its analogues on a chiral stationary phase based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid.

A liquid chromatographic chiral stationary phase, which contains two N-CH3 amide connecting groups, based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was first applied to the resolution of methoxyphenamine (2-methoxy-N-methylamphetamine, a ß-adrenergic receptor agonist used as a bronchodilator). The resolution of methoxyphenamine on the chiral stationary phase containing two N-CH3 amide connecting groups was quite successful with the separation factor (α) of 1.42 and resolution (RS ) of 4.22 compared with those (α of 1.09 and RS of 1.55) on the chiral stationary phase containing two N-H amide connecting groups. In addition, the chiral stationary phase containing two N-CH3 amide connecting groups was applied to the resolution of methoxyphenamine analogues. From the comparison of the resolution results of methoxyphenamine with those of methoxyphenamine analogues on the chiral stationary phase containing two N-CH3 amide connecting groups, the N-methyl group and the 2-methoxyphenyl group of methoxyphenamine were elucidated to be the structurally essential parts for the resolution on the chiral stationary phase.

Chiral separation of (±)-methamphetamine racemate using molecularly imprinted sulfonic acid functionalized resin.

In the present study, a sulfonic acid functionalized enantio-selective resinous material was developed for effective chiral separation of (±)-methamphetamine racemate. R-methamphetamine-sulfonamide phenolic derivative was first prepared and fully characterized utilizing instrumental and spectroscopic techniques, then the sulfonamide was implemented in an acid catalyzed condensation copolymerization with phenol and formaldehyde. The resulted resinous material was then exposed to successive alkaline and acidic treatments in order to remove the R-methamphetamine enantiomer out of the resin matrix and obtaining the molecularly imprinted enantio-selective material, which was also investigated by scanning electron microscope, FTIR and XPS spectroscopy. The maximum selective extraction of the R-methamphetamine enantiomer was achieved at pH 7. The adsorption isotherms indicated an adsorption capacity of 233 ±â€¯1 mg/g and followed the well-known Langmuir model. Also, the enantio-separation experiment of the racemic mixture was performed by column technique and both the supernatant loading and the eluant recovery solutions indicated an enantiomeric excess of 80% and 67% related to S- and R-methamphetamine, respectively.

Simultaneous enantioseparation of methcathinone and two isomeric methylmethcathinones using capillary electrophoresis assisted by 2-hydroxyethyl-ß-cyclodextrin.

Methcathinone (ephedrone), 4-methylmethcathinone (mephedrone), and 3-methylmethcathinone (metaphedrone) are toxicologically-important cathinone derivatives used commonly as designer drugs. In this work we show the first method allowing to separate simultaneously all these molecules in a chiral medium, ensuring good resolution between all enantiomers. Eight cyclodextrins have been tested as potential chiral selectors, the best results were obtained with 2-hydroxyethyl-ß-cyclodextrin, unreported so far for efficient separation of cathinones. After optimization, the method was calibrated and validated with and without the use of internal standard. The addition of standard improved an overall repeatability and precision, the use of electrophoretic mobility ratio was especially favorable (RSD < 1%). It was demonstrated that the method may be easily extended by introducing the additional cathinone-related drugs to the sample, maintaining satisfactory separation efficiency.

Solid-phase extraction followed by liquid chromatography-high resolution mass spectrometry to determine synthetic cathinones in different types of environmental water samples.

Synthetic cathinones have become popular in recent years, which would explain why their determination in influent sewage samples has already been documented. In the present study a method based on solid-phase extraction followed by liquid chromatography and high resolution mass spectrometry is developed, validated and applied to determine twelve cathinones and one of their metabolites in different environmental samples including influent and effluent sewage and river water. Two cation-exchange sorbents (Oasis MCX and Oasis WCX) were compared, with better results achieved with Oasis WCX in terms of apparent recoveries (70-100%) and matrix effects (lower than -34%). The method was validated with effluent sewage samples providing suitable figures of merit, with method quantification limits ranging from 1ng/L to 5ng/L and method detection limits from 0.1ng/L to 0.5ng/L for all the compounds. Of the different cathinones studied, three, namely methylone, mephedrone metabolite and methylenedioxypyrovalerone, were quantified at concentration levels of low ng/L in each of the different samples analysed, while a number of the other cathinones were also detected in some of the samples.

Peptide Metal-Organic Frameworks for Enantioselective Separation of Chiral Drugs.

We report the use of a chiral Cu(II) 3D metal-organic framework (MOF) based on the tripeptide Gly-l-His-Gly (GHG) for the enantioselective separation of metamphetamine and ephedrine. Monte Carlo simulations suggest that chiral recognition is linked to preferential binding of one of the enantiomers as a result of either stronger or additional H-bonds with the framework that lead to energetically more stable diastereomeric adducts. Solid-phase extraction of a racemic mixture by using Cu(GHG) as the extractive phase permits isolating >50% of the (+)-ephedrine enantiomer as target compound in only 4 min. To our knowledge, this represents the first example of a MOF capable of separating chiral polar drugs.

Separation of ortho, meta and para isomers of methylmethcathinone (MMC) and methylethcathinone (MEC) using LC-ESI-MS/MS: Application to forensic serum samples.

Separation and identification of positional isomers is an important issue in forensic toxicology, particularly in the context of new psychoactive substances (NPS). Despite the structural similarity, positional isomers often show different pharmacological properties and thus can exhibit dramatic differences with respect to their toxicity. Additionally, besides these pharmacological and toxicological effects, the legal status is also of great importance. We present a sensitive and selective LC-MS/MS method to separate the ortho, meta and para isomers of methylmethcathinone (MMC) and methylethcathinone (MEC) using a core-shell biphenyl analytical column. Reliability of the method was confirmed under consideration of the validation parameters selectivity, linearity, accuracy and precision, analytical limits, processed sample stability, matrix effects and recovery. Linearity was demonstrated over the entire calibration range from 5 to 250ng/ml with the use of a 1/x2 weighting. Appropriate quantification and detection limits (LLOQ=5ng/ml, LOD<2ng/ml) could be achieved. Application of the method to real serum samples collected between June 2014 and August 2016 revealed the proof of a recent MMC or MEC consumption, respectively, in eight cases. Isomers of MMC could be detected in three of these eight cases, of which two were positive for 3-MMC and one was positive for 2-MMC. The other samples were tested positively for 3-MEC. In none of the samples 4-MMC, 2-MEC or 4-MEC could be detected. Only substances that were not governmentally controlled at that time could be detected, reflecting the rapid response of the recreational drug market to newly enacting drug laws.