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101.
Barroso M Gallardo E Vieira DN Queiroz JA López-Rivadulla M 《Analytical and bioanalytical chemistry》2011,400(6):1665-1690
The use and abuse of illegal drugs affects all modern societies, and therefore the assessment of drug exposure is an important
task that needs to be accomplished. For this reason, the reliable determination of these drugs and their metabolites in biological
specimens is an issue of utmost relevance for both clinical and forensic toxicology laboratories in their fields of expertise,
including in utero drug exposure, driving under the influence of drugs and drug use in workplace scenarios. Most of the confirmatory
analyses for abused drugs in biological samples are performed by gas chromatographic–mass spectrometric methods, but use of
the more recent and sensitive liquid chromatography–(tandem) mass spectrometry technology is increasing dramatically. This
article reviews recently published articles that describe procedures for the detection of opiates in the most commonly used
human biological matrices, blood and urine, and also in unconventional ones, e.g. oral fluid, hair, and meconium. Special
attention will be paid to sample preparation and chromatographic analysis. 相似文献
102.
The present work demonstrates the successful application of automated biocompatible in-tube solid-phase microextraction coupled with liquid chromatography (in-tube SPME/LC) for determination of interferon alpha(2a) (IFN α(2a)) in plasma samples for therapeutic drug monitoring. A restricted access material (RAM, protein-coated silica) was employed for preparation of a lab-made biocompatible in-tube SPME capillary that enables the direct injection of biological fluids as well as the simultaneous exclusion of macromolecules by chemical diffusion barrier and drug pre-concentration. The in-tube SPME variables, such as sample volume, draw/eject volume, number of draw-eject cycles, and desorption mode were optimized, to improve the sensitivity of the proposed method. The IFN α(2a) analyses in plasma sample were carried out within 25min (sample preparation and LC analyses). The response of the proposed method was linear over a dynamic range, from 0.06 to 3.0MIUmL(-1), with correlation coefficient equal to 0.998. The interday precision of the method presented coefficient of variation lower than 8%. The proposed automated method has adequate analytical sensitivity and selectivity for determination of IFN α(2a) in plasma samples for therapeutic drug monitoring. 相似文献
103.
Monica Felts de La Roca Soares José Lamartine Soares-Sobrinho Keyla Emanuelle Ramos da Silva Lariza Darlene Santos Alves Pablo Queiroz Lopes Lidiane Pinto Correia Fábio Santos de Souza Rui Oliveira Macêdo Pedro José Rolim-Neto 《Journal of Thermal Analysis and Calorimetry》2011,104(1):307-313
The ornidazole drug substance presents melt at approximately 90 °C (∆T = 85–98 °C), which is critical for its use on pharmaceutical manufacturing process. This work aimed the thermal characterization
of ornidazole raw-material synthesized by three different manufacturers from India, China, and Italy, using the thermoanalytical
techniques of DTA, DSC, and TG, besides the verification of its stability and compatibility as a solid pharmaceutical product
by the analysis of its binary mixtures (BM) with excipients and a tablet formulation. The characterization includes the thermal
decomposition kinetic investigation by Ozawa model using Arrhenius equation and drug purity determination by Van’t Hoff equation.
The DSC purity determination and precision were compared with results from UV–Vis spectrophotometric and liquid chromatography,
showing an adequate correlation before being recommended as a general method for purity assay. The drug raw-materials presented
similar quality and zero-order kinetic behavior, besides showing differences on thermal stability. The drug presented compatibility
with the tested excipients since the BM studied presented melting at the same temperature range as the drug and a decomposition
temperature similar to the drug for two of the BM, and at a higher temperature for the others three of the BM evaluated, which
presented excipients with higher molecular structure, capable of spatial coating on the small drug molecule promoting a physical
interaction pharmaceutical acceptable. The tablet was processed by wet granulation and compressed under normal conditions
of pressure and temperature, maintaining the physical properties of solid drug approving the manufacturing process used. In
this study, the thermal analysis was used with success as an alternative method to characterize, quantify, and perform a preformulation
study. 相似文献
104.
P. S. Epaminondas K. L. G. V. Araújo J. A. Nascimento M. C. D. Silva R. Rosenhaim L. E. B. Soledade N. Queiroz A. L. Souza I. M. G. Santos A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2011,106(2):545-550
Physico-chemical properties, spectroscopy, and thermal analyses were used aiming at evaluating the influence of toasting and
of the flaxseed variety on thermo-oxidative behavior of flaxseed oils. Thermogravimetry (TG) and differential scanning calorimetry
(DSC) were associated to gas chromatography, infrared spectroscopy and UV–Vis spectroscopy, as well as to physico-chemical
analyses to characterize the oils obtained from raw and toasted flaxseeds. No meaningful differences in the thermal and oxidative
stabilities were noticed comparing oils obtained from the brown and the golden flaxseeds. Nevertheless, the UV–Vis spectra
indicated that both flaxseed oils were at the beginning of the oxidation process. The previous toasting of the seeds led to
a higher oxidation for both varieties being harmful to the flaxseed oil quality. 相似文献
105.
P. S. Epaminondas K. L. G. V. Araújo A. Lima de Souza M. C. D. Silva N. Queiroz A. L. Souza L. E. B. Soledade I. M. G. Santos A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2011,106(2):551-555
Chemical and thermal analyses of golden and brown flaxseeds were carried out for raw and toasted seeds aiming at evaluating
their nutritional and thermo-oxidative properties. Moisture, lipids, protein, soluble carbohydrates, and ash contents were
quantified. Concerning lipids and proteins, in average, no meaningful differences were observed for the two varieties, being
also equivalent to the literature data. The golden variety had a lower amount of fibers and a higher amount of soluble carbohydrates
than the brown variety. The techniques of thermogravimetry and differential scanning calorimetry were applied for elucidating
the thermal degradation process of the seeds. The toasted gold and brown seeds were more stable to thermal decomposition than
the raw seeds, under oxidative conditions. Golden seeds seem to be more susceptible to oxidation than brown seeds, under toasting
conditions. Finally, no meaningful advantages were observed for the golden seeds in comparison to the brown ones. 相似文献
106.
G. A. A. Teixeira A. S. Maia R. Rosenhaim I. M. G. Santos A. L. Souza A. G. Souza N. Queiroz 《Journal of Thermal Analysis and Calorimetry》2011,106(2):569-574
Biodiesel can be obtained from various fatty acid sources. Each raw material has a different chemical composition that leads
to different properties. Owing to these properties, the mixture of different proportions of raw materials can lead to biodiesels
with best features in relation to physicochemical parameters such as viscosity, oxidative stability and flow properties, generating
a fuel whose characteristics meet the requirements of the current legislation of the Brazilian National Agency of Petroleum,
Natural Gas and Biofuels (ANP). The objective of this study was to determine the physicochemical properties of biodiesel samples
produced from mixtures of beef tallow, babassu oil, and soybean oil. The thermo-oxidative stability was evaluated using thermogravimetry
(TG/DTG) and differential scanning calorimetry (DSC). The results showed that all samples were in accordance to the ANP specifications.
The biodiesel obtained from a mixture containing 50% of babassu oil had lower values of pour point, cold filter plugging point,
and freezing point. This biodiesel also showed a higher thermo-oxidative stability in synthetic air and in oxygen atmospheres. 相似文献
107.
Queiroz LH Lacerda V dos Santos RB Greco SJ Cunha Neto A de Castro EV 《Magnetic resonance in chemistry : MRC》2011,49(3):140-146
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 (1)H and (13)C NMR signals and the relative stereochemistry of the 1,6-epoxycarvone and the α-epoxypinene. All the (1)H and (13)C 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. 相似文献
108.
Calhelha RC Ferreira IC Peixoto D Abreu RM Vale-Silva LA Pinto E Lima RT Alvelos MI Vasconcelos MH Queiroz MJ 《Molecules (Basel, Switzerland)》2012,17(4):3834-3843
Three aminodi(hetero)arylamines were prepared via a palladium-catalyzed C-N Buchwald-Hartwig coupling of methyl 3-aminothieno[3,2-b]pyridine-2-carboxylate with different bromonitrobenzenes, followed by reduction of the nitro groups of the coupling products to the corresponding amino compounds. The aminodi(hetero)arylamines thus obtained were evaluated for their growth inhibitory effect on four human tumor cell lines MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), NCI-H460 (non-small cell lung cancer) and HepG(2) (hepatocellular carcinoma). The toxicity to non-tumor cells was also evaluated using a porcine liver primary cell culture (PLP1), established by us. The aminodi(hetero)arylamine with the NH(2) group in the ortho position and an OMe group in the para position to the NH of the di(hetero)arylamine, is the most promising compound giving the lowest GI(50) values (1.30-1.63 μM) in all the tested human tumor cell lines, presenting no toxicity to PLP1 at those concentrations. The effect of this compound on the cell cycle and induction of apoptosis was analyzed in the NCI-H460 cell line. It was observed that it altered the cell cycle profile causing a decrease in the percentage of cells in the G0/G1 phase and an increase of the apoptosis levels. 相似文献
109.
Research on RNA has led to many important biological discoveries and the improvement of therapeutic technologies. In particular, there is a great focus on small RNA and ribosomal RNA owing to their key functions in the cell, which make them excellent therapeutic targets. Although the study of these RNA classes is progressing, some limitations have been found regarding the use of suitable techniques that are able to produce and isolate biologically competent and chemically stable RNA. To address this, we have developed a novel histidine affinity chromatography-based isolation methodology for small and ribosomal RNA molecules. The new procedure involves three main steps: (1) cell lysis with guanidinium buffer, (2) RNA primary isolation with ammonium sulfate precipitation and (3) histidine affinity chromatography to specifically purify small RNA and ribosomal RNA from other Escherichia coli impurities (genomic DNA and proteins). The RNA quality assessment revealed that both RNA species were obtained with a high recovery, integrity and purity. The potential of this method to achieve a reproducible RNA isolation with appropriate quality has been demonstrated and it should have broad application in the structural, biophysical and biomedical investigation of systems involving RNA components. 相似文献
110.
Srgio L. C. Ferreira Adriana S. Queiroz Marcelo S. Fernandes Hilda C. dos Santos 《Spectrochimica Acta Part B: Atomic Spectroscopy》2002,57(12):1939-1950
In the present paper a procedure for preconcentration and determination of vanadium and copper in seawater using inductively coupled plasma optical emission spectrometry (ICP OES) is proposed, which is based on solid-phase extraction of vanadium (IV), vanadium (V) and copper (II) ions as 1-(2-pyridylazo)-2-naphthol (PAN) complexes by active carbon. The optimization process was carried out using two-level full factorials and Doehlert matrix designs. Four variables (PAN mass, pH, active carbon mass and shaking time) were regarded as factors in the optimization. Results of the two-level full factorial design 24 with 16 runs for vanadium extraction, based on the variance analysis (ANOVA), demonstrated that the factors pH and active carbon mass, besides the interaction (pH×active carbon mass), are statistically significant. For copper, the ANOVA revealed that the factors PAN mass, pH and active carbon mass and the interactions (PAN mass×pH) and (pH×active carbon mass) are statistically significant. Doehlert designs were applied in order to determine the optimum conditions for extraction. The procedure proposed allowed the determination of vanadium and copper with detection limits (3σ/S) of 73 and 94 ng l−1, respectively. The precision, calculated as relative standard deviation (R.S.D.), was 1.22 and 1.37% for 12.50 μg l−1 of vanadium and copper, respectively. The preconcentration factor was 80. The recovery achieved for determination of vanadium and copper in the presence of several cations demonstrated that this procedure improved the selectivity required for seawater analysis. The procedure was applied to the determination of vanadium and copper in seawater samples collected in Salvador City, Brazil. Results showed good agreement with other data reported in the literature. 相似文献