Alvaro C. Neto

Qualitative analysis of designer drugs by paper spray ionisation mass spectrometry (PSI-MS)

The application of ambient ionization mass spectrometry such as paper spray ionisation (PSI) is a fast, powerful, and simple method to analyze designer drugs directly on the surface of blotters. PSI-MS does not require nebulizing gas and heating temperature as well as complex protocols for sample preparation. Herein, it was possible to identify and elucidate the chemical structure of designer drugs using tandem mass spectrometry experiments from a triangular blotter. Substances such as lysergic acid diethylamide (LSD), and five new designer drugs (2,5-dimethoxy-4-chloroamphetamine (DOC), 2,5-dimethoxy-4-bromoamphetamine (DOB), 25C-NBOMe, 25B-NBOMe, and 25I-NBOMe) were characterized by PSI-MS. The PSI(+)-MS and PSI(+)-MS/MS data confirmed the assignments of the designer drugs and fragmentation mechanisms have been proposed. From losses of 17 Da (NH3), which is typical of primary amines, the CID results suggest the presence of isomers in the chemical composition of the NBOMe class. Additionally, the data were compared to those of ultra-high-resolution mass spectroscopy (positive-ion electrospray ionization coupled with Fourier transform ion cyclotron mass spectrometry, ESI(+)FT-ICR MS).

NMR property calculations and experimental study of the 1,6-epoxycarvone and α-epoxypinene: a comparison of models

This work aims at using theoretical calculations of shielding tensors (σ) through different methods [gauge‐independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and individual gauges for atoms in molecules (IGAIM)] and spin‐spin coupling constants J using GIAO method to compare these methods and to corroborate the data obtained with the assignment of all of 1H and 13C NMR signals and the relative stereochemistry of the 1,6‐epoxycarvone and the α‐epoxypinene. All the 1H and 13C NMR signals were assigned unequivocally. The stereochemistry for the epoxides is trans and the B3LYP theory level with CSGT and IGAIM methods is the best choice to evaluate theoretical chemical shifts for compounds studied. Copyright

Análise do teor e da qualidade dos lipídeos presentes em sementes de oleaginosas por rmn de baixo campo

To choose among the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different low-field 1H nuclear magnetic resonance (NMR) experiments with varied pulse sequences, namely single-pulse, spin-echo, CPMG, and CWFP. The experiments that involved the first three sequences showed high correlation with each other and with the solvent extraction method. The quality of the vegetable oils was also evaluated on the basis of the existing correlation between the T2 values of the oils and their properties, such as viscosity, iodine index, and cetane index. These analyses were performed using HCA and PCA chemometric tools. The results were sufficiently significant to allow separation of the oleaginous matrices according to their quality. Thus, the low-field 1H NMR technique was confirmed as an important tool to aid in the selection of oleaginous matrices for biodiesel production.

Triterpenes from Pouteria ramiflora (Mart.) Radlk. Leaves (Sapotaceae)

Pouteria ramiflora (Mart.) Radlk. (Sapotaceae) is a species used by inhabitants from the Cerrado for its edible fruits and medicinal value. Hexane crude extracts from leaves and fractions were evaluated for inxa0vitro α-amylase inhibitory activity and antioxidant potential. The fraction with the highest α-amylase inhibitory activity was submitted to a phytochemical study. Three triterpenes were isolated, friedelin, epi-friedelanol, and taraxerol. This is the first report of these compounds isolated from P.xa0ramiflora. Moreover, this is the first report of friedelin isolated from Pouteria sp. Epi-friedelanol was present in significant amounts, suggesting that this compound could be a candidate marker for this species.

Unequivocal structural assignments of three cycloheptenoid intermediates for guaiane sesquiterpenes: an experimental and theoretical approach.

* Correspondence to: Valdemar Lacerda Jr., Departamento de Química, Centro de Ciências Exatas, Universidade Federal do Espírito Santo, Av. Fernando Ferrari 514, 29.075-910, Vitória, ES, Brazil. E-mail: valdemar.lacerda@ufes.br ** Correspondence to: Timothy J. Brocksom, Departamento de Química, Universidade Federal de São Carlos, 13.565-905, São Carlos, SP, Brazil. E-mail: brocksom@terra.com.br, www.lqbo.ufscar.br

Niobium(V) chloride as catalyst in Diels-Alder reaction of furan ring

According to the relevant literature, the Diels-Alder reaction of furan without a catalyst can last several weeks and shows a low yield due to the dienes low reactivity. The use of Lewis acid catalysts or high pressures is described as an effective method for improving the reaction yields. This paper describes our recent study on the use of niobium pentachloride as the catalyst in Diels-Alder reactions between furan and several reactive dienophiles, among which methyl acrylate showed good yields, especially at lower temperatures. Other dienophiles have shown lower yields because of problems such as byproduct formation and the high reversibility of the reaction.

Extraction and isolation of cannabinoids from marijuana seizures and characterization by 1H NMR allied to chemometric tools

Marijuana, a drug derived from the Cannabis sativa L. plant, is the worlds most consumed illicit drug. In this paper, a total of 156 marijuana samples seized in the state of Espírito Santo (ES), Brazil were studied and analysed by proton nuclear magnetic resonance (1H NMR) spectroscopy to identify the major cannabinoids present. A crude extract of all samples was purified using high performance liquid chromatography so that these compounds could serve as reference substances. Nine fractions were obtained and analysed by 1H NMR and gas chromatography-mass spectrometry (GC-MS), with five presented cannabinoids. ∆9-THC (Δ9-trans-tetrahydrocannabinol), ∆9-THCA (∆9-tetrahydrocannabinolic acid), ∆8-THC (∆8-tetrahydrocannabinol), 11-hydroxycannabinol, CBV (cannabivarin), and CBN (cannabinol) were found, and their chemical structures were confirmed by GC-MS. The latter compound was obtained with high purity (≈100%), while the others were obtained as less complex mixtures with purity higher than 75% (except for Δ8-THC). Principal component analysis (PCA) was used on the 1H NMR spectra of the 156 samples, and it was found that the samples were grouped according to the months, differentiating into two groups (from July 2014 to January 2015 and from February 2015 to July 2015), where non-grouping was observed from four macro-regions of the ES state (North, Central, Metropolitan, and South). The chemical profile of the seized samples was correlated to the 1H NMR spectrum of an isolated CBN sub-fraction, in which the group formed by samples seized in the year 2015 presented lower CBN content in the chemical composition. From the PCA score plot, two groups of samples were confirmed using the partial least squares discriminant analysis and orthogonal projections to latent structures classification methods.

Quantification of cocaine and its adulterants by nuclear magnetic resonance spectroscopy without deuterated solvents (No-D qNMR)

In this study, a new method was developed to quantify cocaine and some adulterants (lidocaine, caffeine, phenacetin, procaine and benzocaine) using nuclear magnetic resonance spectroscopy without the use of deuterated solvents (No-D qNMR). No-D qNMR presents as main advantages: low cost (in comparison to the use of deuterated solvents), non-destructive and rapid analysis, and being able to detect non-volatile compounds. For analytical validation achievement, figures of merit such as selectivity and specificity, linearity, quantification limit, detection limit, accuracy, precision and robustness were obtained. The built models presented excellent precision ( 0.99), and LOD values which varied between 0.126 and 0.666 mg mL−1. With the purpose of verifying the predictive capacity of the models, 34 crack samples seized by the Civil Police of Espirito Santo State – Brazil were analyzed, and the average cocaine content found was around 17.5 wt%, which is in line with expectations (up to approximately 30 wt%). Moreover, 50 wt% of the samples contained phenacetin, 9 wt% caffeine, and 3 wt% procaine and lidocaine, while benzocaine wasnt identified.

SÍNTESE E DETERMINAÇÃO DA ESTEREOQUÍMICA RELATIVA DE UM NOVO EPÓXIDO ALDEÍDO CICLOPENTANO MONOTERPENÓIDE

In this study, we report the preparation of a new tetra-substituted epoxide aldehyde cyclopentane, which acts as a starting material for the synthesis of plinol, from (R)-(+)-epoxy-limonene. The synthesis was performed in three steps and resulted in a good yield. The structural determination was performed by 1H and 13C NMR, and the relative stereochemistry was defined by nuclear Overhauser effect (NOE) experiments with computer calculations of molecular modeling, particularly with respect to indirect coupling constant calculations.