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.

Magnetic surface-imprinted polymer microspheres coupled with HPLC-MS/MS for sensitive detection of amphetamine-type drugs in water.

Magnetic surface imprinted polymer microspheres (Fe3O4@MIPs) were successfully synthesized via Pickering emulsion polymerization, utilizing N-Methylphenethylamine as a surrogate template for amphetamine-type drugs. Fe3O4@MIPs not only possessed excellent dispersibility and enough magnetic properties in aqueous solutions, but also displayed good selectivity towards six amphetamines, with an imprinting factor ranging from 1.8 to 2.6. The adsorption kinetics closely aligned with the pseudo-second-order model, and the adsorption efficiency exceeds 80 % for each amphetamine at equilibrium. Fe3O4@MIPs were then employed as the efficient adsorbents for the extraction of amphetamine drugs. Extraction parameters, including sample pH, the mass of adsorbent, and the type and volume of eluting solvent, were carefully optimized. In combination with the high performance liquid chromatography tandem triple quadrupole mass spectrometry (HPLC-MS/MS), a selective magnetic solid-phase extraction (MISPE) method utilizing Fe3O4@MIPs was developed for the detection of six amphetamines in water samples. The limits of detection and limits of quantitation were determined to be 5.2∼23 ng L-1 and 17∼77 ng L-1, respectively. Recoveries for the six target drugs from lake water and sewage samples fell within the range of 87.2∼110 %. Additionally, the MISPE-HPLC-MS/MS method exhibited excellent repeatability, with a precision below 8.5 % at two spiking levels. The prepared Fe3O4@MIPs possessed the advantages of high selectivity, straightforward preparation, facile separation and good reusability, and was highly suitable for the efficient extraction of amphetamine-type substances in complex environmental water.

Chiral analysis of amphetamine, methamphetamine, MDMA and MDA enantiomers in human hair samples.

A novel analytical method was developed for the simultaneous quantification of the R/S-enantiomers of amphetamine, methamphetamine, MDA and MDMA in hair samples using liquid chromatography-tandem mass spectrometry (LC-MS-MS). This method involved a straightforward derivatization step with dansyl chloride and the use of a chiral column, enabling the separation and quantification of all eight enantiomers in a single analysis. The method exhibited excellent linearity across a concentration range of 0.03-3.00 ng/mg for each enantiomer. Precision and accuracy were within acceptable limits, with bias and relative standard deviation (RSD) values consistently below 6% and 9%, respectively. Selectivity and specificity assessments confirmed the absence of any interference from contaminants or co-extracted drugs. The method demonstrated high sensitivity, with limits of detection (LOD) below 8 pg/mg and limits of quantification (LOQ) below 19 pg/mg for all analytes. Extraction recovery exceeded 79%, and matrix effects were minimal for all analytes. Processed sample stability evaluations revealed consistent results with deviations below 11% for all analytes. Application of the method to 32 authentic human hair samples provided valuable insights into amphetamine use patterns, allowing differentiation between medical amphetamine consumption and illicit use based on enantiomeric composition. Additionally, the method detected co-use of methamphetamine, MDA or MDMA in some samples, highlighting its applicability in drug monitoring and real-life case scenarios within a forensic institute. This innovative analytical approach offers a sensitive and selective method for enantiomeric differentiation of amphetamine, methamphetamine, MDA and MDMA in human hair samples, providing a valuable tool for forensic and clinical investigations.

Structural insights into vesicular monoamine storage and drug interactions.

Biogenic monoamines-vital transmitters orchestrating neurological, endocrinal and immunological functions1-5-are stored in secretory vesicles by vesicular monoamine transporters (VMATs) for controlled quantal release6,7. Harnessing proton antiport, VMATs enrich monoamines around 10,000-fold and sequester neurotoxicants to protect neurons8-10. VMATs are targeted by an arsenal of therapeutic drugs and imaging agents to treat and monitor neurodegenerative disorders, hypertension and drug addiction1,8,11-16. However, the structural mechanisms underlying these actions remain unclear. Here we report eight cryo-electron microscopy structures of human VMAT1 in unbound form and in complex with four monoamines (dopamine, noradrenaline, serotonin and histamine), the Parkinsonism-inducing MPP+, the psychostimulant amphetamine and the antihypertensive drug reserpine. Reserpine binding captures a cytoplasmic-open conformation, whereas the other structures show a lumenal-open conformation stabilized by extensive gating interactions. The favoured transition to this lumenal-open state contributes to monoamine accumulation, while protonation facilitates the cytoplasmic-open transition and concurrently prevents monoamine binding to avoid unintended depletion. Monoamines and neurotoxicants share a binding pocket that possesses polar sites for specificity and a wrist-and-fist shape for versatility. Variations in this pocket explain substrate preferences across the SLC18 family. Overall, these structural insights and supporting functional studies elucidate the mechanism of vesicular monoamine transport and provide the basis to develop therapeutics for neurodegenerative diseases and substance abuse.

Determination of amphetamine enantiomers in urine by conductive vial electromembrane extraction and ultra-high performance supercritical fluid chromatography tandem mass spectrometry.

Separation and quantification of amphetamine enantiomers are commonly used to distinguish between consumption of prescription amphetamine (mostly S-amphetamine) and illicit forms of the drug (racemate). In this study, electromembrane extraction with prototype conductive vials was combined with ultra-high performance supercritical fluid chromatography (UHPSFC-MS/MS) to quantify R- and S-amphetamine in urine. Amphetamine was extracted from 100 µL urine, diluted with 25 µL internal standard solution and 175 µL 130 mM formic acid, across a supported liquid membrane (SLM) consisting of 9 µL of a 1:1(w/w) mixture of 2-nitrophenyloctyl ether (NPOE) and bis(2-ethylhexyl)phosphite (DEHPi) into an acceptor phase containing 300 µL 130 mM formic acid. The extraction was facilitated by the application of 30 V for 15 min. Enantiomeric separation was achieved using UHPSFC-MS/MS with a chiral stationary phase. The calibration range was 50-10,000 ng/mL for each enantiomer. The between-assay CV was ≤5%, within-assay CV ≤ 1.5%, and bias within ±2%. Recoveries were 83%-90% (CV ≤ 6%), and internal standard corrected matrix effects were 99-105 (CV ≤ 2%). The matrix effects ranged from 96% to 98% (CV ≤ 8%) when not corrected by the internal standard. The EME method was compared with a chiral routine method that employed liquid-liquid extraction (LLE) for sample preparation. Assay results were in agreement with the routine method, and the mean deviation between methods was 3%, ranging from -21% to 31%. Finally, sample preparation greenness was assessed using the AGREEprep tool, which resulted in a greenness score of 0.54 for conductive vial EME, opposed to 0.47 for semi-automated 96-well LLE.

Derivatization-assisted immunoassays: application for group-specific detection of potent methamphetamine and amphetamine enantiomers.

Reliable and feasible tools for detecting (S)-methamphetamine [(S)-MAP] and (S)-amphetamine [(S)-AP] are required for regulating their illicit circulation. Antibodies that react equally to these stimulants are desirable for this purpose, but have been difficult to generate because of the crucial difference between their characteristic structures: i.e., N-methylamino (MAP) and amino (AP) groups. Furthermore, their small molecular masses (Mr < 150) have hampered the generation of high-affinity antibodies. To overcome these problems, we converted (S)-MAP and -AP into their 2-(trimethylsilyl)ethyl carbamate forms, Teoc-(S)-MAP and -AP, respectively, as surrogate analytes. The Teoc-derivatization not only increases their molecular masses, but also masks their structural differences. We generated a novel monoclonal antibody that showed a satisfactory affinity to Teoc-(S)-MAP residues (Kd = 13 nM as the IgG form) and developed a competitive enzyme-linked immunosorbent assay (ELISA) using microplates containing immobilized Teoc-(S)-MAP residues. Almost overlapping dose-response curves were obtained for Teoc-(S)-MAP and -AP, with the limit of detection of 0.078 and 0.10 ng per assay, respectively. A fixed amount of test powder sample (1 mg) was derivatized with Teoc-O-succinimidyl for 5 min, and subjected to ELISA using Teoc-(S)-MAP as the calibration standard. Under this protocol, (S)-MAP and -AP were converted to their Teoc derivatives with 30% and 34% yield, respectively, determined using ELISA as "Teoc-(S)-MAP equivalent," being distinguished from the derivatization products of (R)-MAP, (R)-AP, ephedrine, (S)-methylenedioxymethamphetamine, tyramine, dopamine, and ß-alanine. This ELISA detected as little as 10 µg of (S)-MAP and -AP, and (S)-MAP in urine obtained from (S)-MAP-administered rats. Immunochromatography devices were also developed using gold nanoparticles coated with the monoclonal antibody, with which 0.10 mg of (S)-MAP and -AP was detected by the naked eye. We conclude that the present derivatization-assisted immunoassays may be useful for the detection of (S)-MAP and/or -AP in early stage screening of suspicious substances.

Amphetamine or skin cream? The impact of the sampling site on the concentration of controlled substances: a case report.

This case report demonstrates the impact of different sampling sites on the quantification of narcotic substances. In 2020, officers secured a syringe containing a light-yellow paste-like substance, for which a drug pre-test indicated a positive result for amphetamine, inducing subsequent analyses of the sample by means of a gaschromatographic-mass spectrometric method (GC-MS) and liquid chromatography-(tandem) mass spectrometry (LC-MS/MS). Depending on the sample location, different results were obtained, with amphetamine not being detected in each sample. Amphetamine was particularly found at the outlet of the syringe, while amphetamine detection on the inside of the syringe at the plunger seal was only possible occasionally and, moreover, in lower concentrations. Based on this and with regard to the comparatively small amphetamine concentrations, contamination of the syringe (especially on the tip of the syringe) was assumed. Hence, the results strengthened the importance of the implication of different sampling sites, when either homogenization of the sample is not feasible or is not performed for reasons of plausibility checks concerning possible contamination of the sample.

Determination of the enantiomeric composition of amphetamine, methamphetamine and 3,4-methylendioxy-N-methylamphetamine (MDMA) in seized street drug samples from southern Germany.

Amphetamine (speed), methamphetamine (crystal meth), and 3,4-methylenedioxy-N-methylamphetamine (MDMA, ecstasy) represent the most frequently abused amphetamine-type stimulants (ATS). Differences in pharmacological potency and metabolism have been shown for the enantiomers of all three stimulants. Legal consequences in cases of drug possession may also differ according to the German law depending on the enantiomeric composition of the seized drug. Therefore, enantioselective monitoring of seized specimens is crucial for legal and forensic casework. Various kinds of samples of amphetamine (n = 143), MDMA (n = 94), and methamphetamine (n = 528) that were seized in southern Germany in 2019 and 2020 were analyzed for their chiral composition using different chromatographic methods. Whereas all samples of amphetamine and MDMA were racemic mixtures, the chiral composition of the methamphetamine specimens was diverse. Although the vast majority (n = 502) was present as (S)-methamphetamine, also specimens containing pure (R)-methamphetamine (n = 7) were found. Furthermore, few samples (n = 8) were of racemic nature or contained non-racemic mixtures of both enantiomers (n = 10). Because methamphetamine appears in varying enantiomeric compositions, any seizure should be analyzed using an enantioselective method. Amphetamine and MDMA, on the other hand, currently appear to be synthesized exclusively via racemic pathways and are not chirally purified. Nevertheless, regular monitoring of the chiral composition should be ensured.

DFT-D4 Insight into the Inclusion of Amphetamine and Methamphetamine in Cucurbit[7]uril: Energetic, Structural and Biosensing Properties.

The host-guest interactions of cucurbit[7]uril (CB[7]) as host and amphetamine (AMP), methamphetamine (MET) and their enantiomeric forms (S-form and R-form) as guests were computationally investigated using density functional theory calculations with the recent D4 atomic-charge dependent dispersion corrections. The analysis of energetic, structural and electronic properties with the aid of frontier molecular orbital analysis, charge decomposition analysis (CDA), extended charge decomposition analysis (ECDA) and independent gradient model (IGM) approach allowed to characterize the host-guest interactions in the studied systems. Energetic results indicate the formation of stable non-covalent complexes where R-AMP@CB[7] and S-AMP@CB[7] are more stable thermodynamically than R-MET@CB[7] and S-MET@CB[7] in gas phase while the reverse is true in water solvent. Based on structural analysis, a recognition mechanism is proposed, which suggests that the synergistic effect of van der Waals forces, ion-dipole interactions, intermolecular charge transfer interactions and intermolecular hydrogen bonding is responsible for the stabilization of the complexes. The geometries of the complexes obtained theoretically are in good agreement with the X-ray experimental structures and indicate that the phenyl ring of amphetamine and methamphetamine is deeply buried into the cavity of CB[7] through hydrophobic interactions while the ammonium group remains outside the cavity to establish hydrogen bonds with the portal oxygen atoms of CB[7].

Assessing Palatability of a New Amphetamine Extended-Release Tablet Formulation for the Treatment of ADHD.

INTRODUCTION/OBJECTIVE: ADHD is, for many people, a lifelong disease that requires chronic medication use. Stimulant therapy is often recommended as first-line treatment for ADHD. Adherence to stimulant treatment among patients diagnosed with ADHD is poor. Major regulatory agencies have recommended measurement of palatability for new tablet formulations. A new amphetamine extended-release tablet (AMPH ER TAB) for the treatment of attention-deficit/hyperactivity disorder (ADHD) was developed. The AMPH ER TAB has a bubblegum flavor and can be chewed or swallowed whole. In 2016, the FDA developed a draft guidance document on the topic of chewable drug tablet formulation palatability. METHODS: A palatability study of the AMPH ER TAB using the 2016 FDA guidance was conducted. Subjects were asked to assess the taste, aftertaste, and mouthfeel of the tablet formulation using a short questionnaire. Scores from the questionnaire were rated and presented. RESULTS: The substudy assessed 35 subjects with a mean age of 38 (±11) years. Subjects were predominantly male, non-Hispanic, and White. Most subjects rated the oral sensation/mouth feel and taste of the tablet as positive (pleasant to very pleasant) (70.1% and 83.6%, respectively). Additionally, 86.6% of the subjects rated the strength of the taste as neutral (moderate taste) or positive (mild to no taste). Finally, 82.1% of all subjects rated the aftertaste as positive (pleasant to very pleasant) and 92.5% of subjects rated the strength of the aftertaste as neutral or positive (mild to no taste). The trends in evaluation scores for each question were similar regardless of whether the ER chewable tablet was administered under fasted or fed conditions. CONCLUSION: The positive palatability data presented here will be useful for future "real-world" assessments of adherence to treatment with the AMPH ER TAB. Enhanced adherence may bolster the argument that taste, mouthfeel, and aftertaste are critical determinants of treatment adherence.

Identification of amphetamine as a stimulant drug by pristine and doped C70 fullerenes: a DFT/TDDFT investigation.

The density functional theory (DFT) was used to examine the electronic reactivity and sensitivity of a pristine, Si, and Al-doped fullerene C70 with AM drug. AM drug has been shown to be physically absorbed by its N-head on the pristine C70 with an adsorption energy of about - 1.09 kcal/mol and to have no impact on the electric conductivity of that cluster. The atom substitution of Si and Al for C atoms at C70 significantly increases C70 fullerene reactivity, with adsorption energy predictions of approximately - 31.09 and - 45.59 kcal/mol, respectively. The energy difference of LUMO and HOMO, i.e., Eg from C70 fullerene, significantly affects AM drug. Significant LUMO destabilization in Al-C70 by adsorption of the drug AM boosts the electrical conductivity of Al-C70 while generating electric signals that are related to the environmental presence of AM drug. Hence, Al-doped C70 is demonstrated to be an effective electronic AM drug sensor. In contrast to Si-C70 fullerene, significant AM-drug adsorption effects on Fermi and Si-C70 work functions make Si-C70 an Ф-type candidate for AM drug sensor applications. The time-dependent theory of the functional density shows that the AM/Al-C70 complex is steadily situated at a maximum peak of 784.15 nm.

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.

Enantiomeric separation and quantification of R/S-amphetamine in serum using semi-automated liquid-liquid extraction and ultra-high performance supercritical fluid chromatography-tandem mass spectrometry.

The amphetamine molecule contains a chiral center and its enantiomers exhibit differences in pharmacological effects, with the S-enantiomer mediating most of the central nervous system stimulating activity. The majority of prescribed amphetamine consists of the pure S-enantiomer, but therapeutic formulations containing the R-enantiomer in various proportions are also available. Illegal amphetamine remains available mainly as a racemic mixture of the R- and S-enantiomers. To distinguish between legal and illegal consumption of amphetamine a method for enantiomeric separation and quantification of R/S-amphetamine in serum was developed and validated using ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS). Sample preparation prior to UHPSFC-MS/MS analysis was performed by a semi-automated liquid-liquid extraction method. The UHPSFC-MS/MS method used a Chiralpak AD-3 column with a mobile phase consisting of CO2 and 0.1% ammonium hydroxide in 2-propanol/methanol (50/50, v/v). The injection volume was 2 µL and run time was 4 minutes. MS/MS detection was performed with positive electrospray ionization and two multiple reaction monitoring transitions (m/z 136.1 > 119.0 and m/z 136.1 > 91.0). The calibration range was 12.5-1,000 nM for each analyte. The between-assay relative standard deviations were in the range of 1.3-3.0%. Recovery was 73% and matrix effects ranged from 95 to 100% when corrected with internal standard. After development and validation, the method has been successfully implemented in our laboratory for both separation and quantification of R/S-amphetamine and has proved to be a reliable and useful tool for distinguishing intake of R- and S-amphetamine in authentic patient samples.

Para-Halogenation of Amphetamine and Methcathinone Increases the Mitochondrial Toxicity in Undifferentiated and Differentiated SH-SY5Y Cells.

Halogenation of amphetamines and methcathinones has become a common method to obtain novel psychoactive substances (NPS) also called "legal highs". The para-halogenated derivatives of amphetamine and methcathinone are available over the internet and have entered the illicit drug market but studies on their potential neurotoxic effects are rare. The primary aim of this study was to explore the neurotoxicity of amphetamine, methcathinone and their para-halogenated derivatives 4-fluoroamphetamine (4-FA), 4-chloroamphetamine (PCA), 4-fluoromethcathinone (4-FMC), and 4-chloromethcathinone (4-CMC) in undifferentiated and differentiated SH-SY5Y cells. We found that 4-FA, PCA, and 4-CMC were cytotoxic (decrease in cellular ATP and plasma membrane damage) for both cell types, whereby differentiated cells were less sensitive. IC50 values for cellular ATP depletion were in the range of 1.4 mM for 4-FA, 0.4 mM for PCA and 1.4 mM for 4-CMC. The rank of cytotoxicity observed for the para-substituents was chloride > fluoride > hydrogen for both amphetamines and cathinones. Each of 4-FA, PCA and 4-CMC decreased the mitochondrial membrane potential in both cell types, and PCA and 4-CMC impaired the function of the electron transport chain of mitochondria in SH-SY5Y cells. 4-FA, PCA, and 4-CMC increased the ROS level and PCA and 4-CMC induced apoptosis by the endogenous pathway. In conclusion, para-halogenation of amphetamine and methcathinone increases their neurotoxic properties due to the impairment of mitochondrial function and induction of apoptosis. Although the cytotoxic concentrations were higher than those needed for pharmacological activity, the current findings may be important regarding the uncontrolled recreational use of these compounds.

Amphetamine decorated cationic lipid nanoparticles cross the blood-brain barrier: therapeutic promise for combating glioblastoma.

Combating brain tumors (glioblastoma multiforme or GBM) is a formidable challenge because of the existence of blood-brain barrier (BBB), a tight cellular junction that separates the central nervous system (CNS) and systemic circulation. Such a selectively permeable barrier prevents the entry of therapeutic molecules from blood circulation to brain parenchyma. Towards enhancing the efficacy of brain tumor-selective drug delivery without perturbing the BBB integrity, nanometric drug carriers are increasingly becoming an efficient therapeutic modality in preclinical studies. Psychostimulant drugs such as amphetamine and methylated amphetamine (METH) are known to penetrate the BBB. Still, little effort has been made to exploit them in nano-drug delivery, largely due to their toxicities. Herein, for the first time, we design, synthesize, and formulate three different ß-amphetaminylated cationic lipid nanoparticles. We show that the ß-amphetaminylated cationic lipid nanoparticles are nontoxic and can cross the BBB presumably through active transcytosis. The BBB penetrating ability also depends on the hydrophilic-hydrophobic balance of the lipids, with hexadecyl lipid (16-BACL) nanoparticle showing maximum accumulation in the brain. The lipid nanoparticle of 16-BACL can simultaneously encapsulate paclitaxel and PDL1-siRNA. The dual drug-loaded lipid nanoparticles showed apoptosis driven cellular cytotoxicity against GL261 cells and improved the overall survivability of orthotopic glioblastoma bearing mice compared to their non-targeting counterpart. The present work describes a new class of BBB-crossing lipid nanoparticles and delineates their therapeutic promise against glioblastoma.

Characterization of an Amphetamine Interference from Gabapentin in an LC-HRMS Method.

An amphetamine interference was observed during the development of an liquid chromatography-high-resolution mass spectrometry (LC-HRMS) multi-class confirmation method for the determination of 47 drugs and metabolites in urine. The interference passed all qualitative criteria for amphetamine leading to potential false-positive results. Upon investigation, it was found that the amphetamine interference was correlated with the presence of high levels of gabapentin. Gabapentin is routinely detected in patient urine specimens at levels in excess of 1 mg/mL as it is widely prescribed at high doses and does not undergo significant metabolism. The source of the interference was identified as a gabapentin in-source fragment isomeric with protonated amphetamine. Here we describe the characterization of this interference and how its effect was mitigated in the LC-HRMS method.

Quantitative Estimation of 38 Illicit Psychostimulants in Blood by GC-APCI-QTOFMS with Nitrogen Chemiluminescence Detection Based on Three External Calibrators.

A method was developed for quantitative estimation of illicit psychostimulants in blood, with an emphasis on new psychoactive substances, based on gas chromatography nitrogen chemiluminescence detection coupled with atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (GC-NCD-APCI-QTOFMS). Quantitative estimation relied on the NCD's N-equimolar response to nitrogen, using amphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and methylenedioxypyrovalerone as external calibrators for prim-, sec- and tert- amines, respectively. After spiking with 38 stimulants at 3 concentration levels, the donor blood samples were submitted to liquid-liquid extraction at a basic pH followed by acylation with trifluoroacetic anhydride. All but 3 psychostimulants could be analyzed with a limit of quantification (LOQ) of 0.05 mg/L. At LOQ, the coefficient of variation (CV) values for between-day accuracy was 62.3-143.3% (mean, 93.5%; median, 88.5%) and precision 6.6-22.4% (mean, 15.8%; median, 16.1%). In addition, 11 post-mortem blood samples, containing 0.08-2.4 mg/L of amphetamine (n = 5), methamphetamine (n = 4) or MDMA (n = 4), were analyzed by the GC-NCD-APCI-QTOFMS method, and the results were compared with an established electron ionization GC-MS method with appropriate calibration. The agreement between the 2 methods was 62.5-117.3%. Regarding identification, the APCI source permitted detection of the intact precursor ion, or the respective acylation product, for all of the measured compounds. The GC-NCD-APCI-QTOFMS method developed here enables instant quantitative estimation of illicit psychostimulants in blood at reasonable accuracy, without the necessity of possessing the true reference standards for each analyte.

Successful use of a novel lux® i-Amylose-1 chiral column for enantioseparation of "legal highs" by HPLC.

Bath salts, fumigations, cleaners and air fresheners, behind these terms substances are hidden, which count as "Legal Highs". These fancy names are used to pretend Legal Highs as harmless compounds, to circumvent legal regulations for marketing as well as to increase the sales. Besides classic illicit drugs of synthetic origin such as amphetamines, cocaine and MDMA, the trade of these compounds, also known as new psychoactive substances (NPS), is not uncommon today. In many countries, NPS are still not subject to drug control. Among them, there are stimulants such as new amphetamine derivatives or cathinones, which possess a chiral centre. Little is known about the fact that the two possible enantiomers may differ in their pharmacological effect. The aim of this study was to test a novel HPLC column for the enantioseparation of a set of 112 NPS coming from different chemical groups and collected by internet purchases during the years 2010-2018. The CSP, namely Lux® 5 µm i-Amylose-1, LC Column 250 x 4.6 mm, was run in normal phase mode under isocratic conditions, UV detection was performed at 245 nm and 230 nm, injection volume was 10 µl and flow rate was 1 ml/min. With a mobile phase consisting of n-hexane/isopropanol/diethylamine (90:10:0.1), herein, 79 NPS were resolved into their enantiomers successfully, for 37 of them baseline resolution was achieved. After increase of lipophily of the mobile phase to 99:1:0.1, another 27 compounds were baseline separated. It was found that all separated NPS are traded as racemic compounds.

An Explanation about the Use of (S)-Citronellal as a Chiral Derivatizing Agent (CDA) in 1H and 13C NMR for Sec-Butylamine, Methylbenzylamine, and Amphetamine: A Theoretical-Experimental Study.

A chiral derivatizing agent (CDA) with the aldehyde function has been widely used in discriminating chiral amines because of the easy formation of imines under mild conditions. There is a preference for the use of cyclic aldehydes as a CDA since their lower conformational flexibility favors the differentiation of the diastereoisomeric derivatives. In this study, the imines obtained from the reaction between (S)-citronellal and the chiral amines (sec-butylamine, methylbenzylamine, and amphetamine) were analyzed by the nuclear Overhauser effect (NOE). Through NOE, it was possible to observe that the ends of the molecules were close, suggesting a quasi-folded conformation. This conformation was confirmed by theoretical calculations that indicated the London forces and the molecular orbitals as main justifications for this conformation. This conformational locking explains the good separation of 13C NMR signals between the diastereomeric imines obtained and, consequently, a good determination of the enantiomeric excess using the open chain (S)-citronellal as a CDA.