RESUMO
A molecularly imprinted polymer was synthesized and characterized to be used as solid-phase extraction sorbent for simultaneous chlorpyrifos and diazinon and their oxon derivatives. Several imprinted polymers were prepared and evaluated in a retention study of these analytes compared with a non-printed polymer. Several parameters affecting the extraction of imprinted polymer such as washing solvent, composition and volume of the eluting solvent and sample volume, were also investigated. Under the optimum conditions, the developed method provided satisfactory limits of detection ranging between 0.07 µg L-1 to 0.12 µg L-1 and the material showed an excellent reusability (> 50 reuses). The method was applied to the extraction and preconcentration of these analytes in water samples. The average recoveries ranged from 79 ± 6 to 104 ± 3 %.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Impressão Molecular , Praguicidas/análise , Clorpirifos/análise , Clorpirifos/isolamento & purificação , Diazinon/análise , Diazinon/isolamento & purificação , Água Doce/análise , Limite de Detecção , Praguicidas/isolamento & purificação , Polímeros/química , Extração em Fase Sólida , Espectrofotometria UltravioletaRESUMO
A chiral capillary monolithic column for enantiomer separation in capillary electrochromatography was prepared by coating cellulose tris(3,5-dimethylphenylcarbamate) on porous glycidyl methacrylate-co-ethylene dimethacrylate monolith in capillary format grafted with chains of [2(methacryloyloxy)ethyl] trimethylammonium chloride. The surface modification of the monolith by the photografting of [2(methacryloyloxy)ethyl] trimethylammonium chloride monomer as well as the coating conditions of cellulose tris(3,5-dimethylphenylcarbamate) onto the grafted monolithic scaffold were optimized to obtain a stable and reproducible chiral stationary phase for capillary electrochromatography. The effect of organic modifier (acetonitrile) in aqueous mobile phase for the enantiomer separation by capillary electrochromatography was also investigated. Several pairs of enantiomers including acidic, neutral, and basic analytes were tested and most of them were partially or completely resolved under aqueous mobile phases. The prepared monolithic chiral stationary phases exhibited a good stability, repeatability, and column-to-column reproducibility, with relative standard deviations below 11% in the studied electrochromatographic parameters.
RESUMO
The present study describes the phytochemical profile and antioxidant activity of the essential oils of three Piperaceae species collected in the central region of Cuba. The essential oils of Piper aduncum, P. auritum and P. umbellatum leaves, obtained by hydrodistillation, were analyzed by gas chromatography-mass spectrometry. The main components of P. aduncum oil were piperitone (34%), camphor (17.1%), camphene (10.9%), 1,8-cineol (8.7%) and viridiflorol (7.4%), whereas that of P. auritum and P. umbellatum was safrole (71.8 and 26.4%, respectively). The antioxidant properties of the essential oils were also evaluated using several assays for radical scavenging ability (DPPH test and reducing power) and inhibition of lipid oxidation (ferric thiocyanate method and evaluation against Cucurbita seed oil by peroxide, thiobarbituric acid and p-anisidine methods). P. auritum showed the strongest antioxidant activity among the Piper species investigated, but lower than those of butylated hydroxyanisol and propyl gallate.
Assuntos
Antioxidantes/análise , Óleos Voláteis/química , Piper/química , Cuba , Cromatografia Gasosa-Espectrometria de MassasRESUMO
The essential oil of Murraya paniculata L leaves from the mountains of the Central Region of Cuba, obtained by hydrodistillation, was analyzed by gas chromatography-mass spectrometry. Eighteen compounds, accounting for 95.1% of the oil were identified. The major component was beta-caryophyllene (ca. 30%). The antioxidant activity of essential oil was evaluated against Cucurbita seed oil by peroxide, thiobarbituric acid and p-anisidine methods. The essential oil showed stronger antioxidant activity than that of butylated hydroxyanisole and butylated hydroxytoluene, but lower than that of propyl gallate. Moreover, this antioxidant activity was supported by the complementary antioxidant assay in the linoleic acid system and 2, 2'-diphenyl-1-picrylhydrazyl. The essential oil also showed good to moderate inhibitory effects against Klebsiellapneumoniae and Bacillus subtilis.
Assuntos
Anti-Infecciosos/análise , Antioxidantes/análise , Murraya/química , Óleos Voláteis/química , Cuba , Testes de Sensibilidade Microbiana , Óleos Voláteis/isolamento & purificação , Folhas de Planta/químicaRESUMO
Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), followed by multivariate treatment of the spectral data, was used to classify seed oils of the genus Cucurbita (pumpkins) according to their species as C. maxima, C. pepo, and C. moschata. Also, C. moschata seed oils were classified according to their genetic variety as RG, Inivit C-88, and Inivit C-2000. Up to 23 wavelength regions were selected on the spectra, each region corresponding to a peak or shoulder. The normalized absorbance peak areas within these regions were used as predictors. Using linear discriminant analysis (LDA), an excellent resolution among all categories concerning both Cucurbita species and C. moschata varieties was achieved. The proposed method was straightforward and quick and can be easily implemented. Quality control of pumpkin seed oils is important because Cucurbita species and genetic variety are both related to the pharmaceutical properties of the oils.
Assuntos
Cucurbita/embriologia , Óleos de Plantas/classificação , Sementes/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Cucurbita/genética , Análise DiscriminanteRESUMO
Fourier transform infrared spectroscopy (FTIR), followed by multivariate treatment of the spectral data, was used to classify extra virgin olive oils (EVOOs) according to their genetic variety. EVOO samples corresponding to seven different genetic varieties (Arbequina, Borriolenca, Canetera, Farga, Hojiblanca, Picual, and Serrana) were analyzed. The wavelength scale of the FTIR spectra of the oils was divided into 20 regions. The normalized absorbance peak areas within these regions were used as predictor variables. Classification of the EVOO samples according to their genetic variety was achieved by linear discriminant analysis (LDA). A good resolution among all categories was achieved using a LDA model constructed with only nine predictor variables. With this LDA model, 88% of the EVOOs were correctly classified, with assignment probabilities higher than 95%. This method is helpful for olive oil producers because it provides useful information related to the genetic variety of EVOOs, which is required by European Community regulations.