Métodos imunoquímicos para análise de contaminantes ambientais: conceitos, estado da arte e perspectivas

Immunoassay techniques provide simple, powerful and inexpensive methods for analysis of environmental contaminants. However, the acceptance of immunoassays is dependent on the clear demonstration of quality and validity compared to more traditional techniques. In this review, primarily, the understanding and the fundamentals of immunoassay methods are given in order to make good use of immunoassays, especially of EIA tests. Special attention is given to the concepts related to the enzyme-linked immunosorbent assay (ELISA) formats, such as inhibition concentration at 50% (IC50), detection limit (LOD), cross-reactivity (CR %). It is also explained why some immunoassays are quantitative methods whereas others can only be used as screening methods. A list of main commercial kits for detection of priority pollutants is given in order to help analysts. Others formats, such as flow-injection immunoassay analysis (FIIA), immunoassay chromatography and immunosensors are also cited.

Análise enantiosseletiva de fármacos: contribuições da cromatografia líquida de alta eficiência e eletroforese capilar

The demand for analytical methods suitable for accurate and reproducible determination of drug enantiomers has increased significantly in the last years. High-performance liquid chromatography (HPLC) using chiral stationary phases and capillary electrophoresis (CE) are the most important techniques used for this purpose. In this paper, the fundamental aspects of chiral separations using both techniques are presented. Some important aspects for the development of enantioselective methods, particularly for the analysis of drugs and metabolites in biological samples, are also discussed.

Análise de fármacos em material biológico: acoplamento microextração em fase sólida "no tubo" e cromatografia líquida de alta eficiência

A new solid phase microextraction (SPME) system, known as in-tube SPME, was recently developed using an open tubular fused-silica capilary column, instead of an SPME fiber, as the SPME device. On-line in-tube SPME is usually used in combination with high performance liquid chromatography. Drugs in biological samples are directly extracted and concentrated in the stationary phase of capillary columns by repeated draw/eject cycles of sample solution, and then directly transferred to the liquid chromatographic column. In-tube SPME is suitable for automation. Automated sample handling procedures not only shorten the total analysis time, but also usually provide better accuracy and precision relative to manual techniques. In-tube SPME has been demonstrated to be a very effective and highly sensitive technique to determine drugs in biological samples for various purposes such as therapeutic drug monitoring, clinical toxicology, bioavailability and pharmacokinetics.

Isolamento do alcalóide ricinina das folhas de Ricinus communis (Euphorbiaceae) através de cromatografias em contracorrente

Droplet counter-current chromatography, rotation locular counter-current chromatography and high-speed counter-current chromatography were applied to the preparative separation of the alkaloid ricinine from the dichloromethane extracts of Ricinus communis leaves. The solvent system used was composed of dichloromethane-methanol-water (93:35:72 v/v/v) and all techniques led to the isolation of large amounts of the alkaloid. The best result was obtained through HSCCC, since the ricinine yield was respectively 50% and 30% higher than when using RLCCC or DCCC.

Desafios da química analítica frente às necessidades da indústria farmacêutica

The development of liquid chromatography-mass spectrometric (LC-MS) techniques in the last few decades has made possible the analysis of trace amounts of analytes from complex matrices. With LC, the analytes of interest can be separated from each other as well as from the interfering matrix, after which they can be reliably identified thanks to the sensitivity and specificity of MS. LC-MS has become an irreplaceable tool for many applications, ranging from the analysis of proteins or pharmaceuticals in biological fluids to the analysis of toxic substances in environmental samples. In different segments of Brazilian Industry mass spectrometry has an important role, e.g. in the pharmaceutical industry in the development of generic formulations, contributing to the growth of Industry and social inclusion. However, the Brazilian chemists until this moment don't have an effective role in this new segment of the analytical chemistry in Brazil. The present paper shows the actual scenario for mass spectrometry in the pharmaceutical industry, emphasizing the need of a revision of graduation courses to attend the needs of this growing market.

Preparative separation of flavonoids from the medicinal plant Davilla elliptica St. Hill. by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) is a major tool for the fast separation of natural products from plants. It was used for the preparative isolation of the flavonoid monoglucosides present in the aerial parts of the Davilla elliptica St. Hill. (Dilleniaceae). This species is used in Brazilian folk medicine for the treatment of gastric disorders. The optimum solvent system used was composed of a mixture of ethyl acetate-n-propanol-water (140:8:80, v/v/v) and led to a successful separation of quercetin-3-O-alpha-L-rhamnopyranoside and myricetin-3-O-alpha-L-rhamnopyranoside in approximately 3.0 hours with purity higher than 95%. Identification was performed by ¹H NMR, 13C NMR and HPLC-UV-DAD analyses.

A simple and rapid method for urinary acetone analysis by headspace/gas chromatography

Urinalysis of acetone is important to monitor workers occupationally exposed to acetone and/or isopropanol, as well as in diagnosis of some diseases related to lipid metabolism impairment. This work shows a sensitive, simple and rapid static headspace-gas chromatographic procedure for quantitative determination of acetone in urine. The method was applied to measure acetone in 207 samples from general population volunteers, resulting in a mean level of 1.12 mg/L (± 0.47) and a range of 0.20 - 1.95 mg/L. The method is reproducible and reliable, making it suitable for routine analysis of acetone in urine.

Caracterização física, química e ecotoxicológica de efluente da indústria de fabricação de explosivos

The production and use of nitroaromatic explosives have resulted in their dissemination into the environment, where their presence in waterways and soil represents an ecological and health hazard. The hazardous characteristics of these compounds need to be carefully studied, so that the impact of their discharge on the environment can be better evaluated. This work presents the characterization of wastewater from Brazilian TNT industry using as analytical techniques mass spectroscopy, chromatography, toxicity assays and other physico-chemical analyses.

Um espalhador de baixo custo de fase estacionária em placas para cromatografia em camada delgada

Chromatography is a means of separating mixtures into their several components. TLC, mainly a liquid/solid process, is one of the separation techniques most often used. It is indispensable in laboratories dealing with natural products, organic and analytical chemistry. Commercial chromatography plates are offered at relatively high cost. In this work the construction of a hand-operated plate coater of stationary phases of low cost and good reproducibility is described to be used in teaching laboratories and research.

High performance liquid chromatography method for quantification of the N-phenylpiperazine derivative LASSBio-579 in rat plasma

A rapid HPLC analytical method was developed and validated for the determination of the N-phenylpiperazine derivative LASSBio-579in plasma rat. Analyses were performed using a C18 column and elution with 20 mM sodium dihydrogen phosphate monohydrate - methanol. The analyte was monitored using a photodiode array detector (257 nm). Calibration curves in spiked plasma were linear over the concentration range of 0.3-8 mg/mL with determination coefficient > 0.99. The lower limit of quantification was 0.3 mg/mL. The applicability of the HPLC method for pharmacokinetic studies was tested using plasma samples obtained after administration of LASSBio-579 to Wistar rats, showing the specificity of the method.

Determination of cocaine in brazilian paper currency by capillary gas chromatography/mass spectrometry

The presence of illicit drugs such as cocaine and marijuana in US paper currency is very well demonstrated. However, there is no published study describing the presence of cocaine and/or other illicit drugs in Brazilian paper currency. In this study, Brazilian banknotes were collected from nine cities, extracted and analyzed by capillary gas chromatography/mass spectrometry, in order to investigate the presence of cocaine. Bills were extracted with deionized water followed by ethyl acetate. Results showed that 93% of the bills presented cocaine in a concentration range of 2.38-275.10 µg/bill.

Determination of moisture content and water activity in algae and fish by thermoanalytical techniques

The water content in seafoods is very important since it affects their sensorial quality, microbiological stability, physical characteristics and shelf life. In this study, thermoanalytical techniques were employed to develop a simple and accurate method to determine water content (moisture) by thermogravimetry (TG) and water activity from moisture content values and freezing point depression using differential scanning calorimetry (DSC). The precision of the results suggests that TG is a suitable technique to determine moisture content in biological samples. The average water content values for fish samples of Lutjanus synagris and Ocyurus chrysurus species were 76.4 ± 5.7% and 63.3 ± 3.9%, respectively, while that of Ulva lactuca marine algae species was 76.0 ± 4.4%. The method presented here was also successfully applied to determine water activity in two species of fish and six species of marine algae collected in the Atlantic coastal waters of Bahia, in Brazil. Water activity determined in fish samples ranged from 0.946 - 0.960 and was consistent with values reported in the literature, i.e., 0.9 - 1.0. The water activity values determined in marine algae samples lay within the interval of 0.974 - 0.979.

Simultaneous spectrophotometric determination of ezetimibe and simvastatin in pharmaceutical preparations using chemometric techniques

Two spectrophotometric methods are described for the simultaneous determination of ezetimibe (EZE) and simvastatin (SIM) in pharmaceutical preparations. The obtained data was evaluated by using two different chemometric techniques, Principal Component Regression (PCR) and Partial Least-Squares (PLS-1). In these techniques, the concentration data matrix was prepared by using the mixtures containing these drugs in methanol. The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbances in the range of 240 - 300 nm in the intervals with Δλ = 1 nm at 61 wavelengths in their zero order spectra, then, calibration or regression was obtained by using the absorbance data matrix and concentration data matrix for the prediction of the unknown concentrations of EZE and SIM in their mixture. The procedure did not require any separation step. The linear range was found to be 5 - 20 µg mL-1 for EZE and SIM in both methods. The accuracy and precision of the methods were assessed. These methods were successfully applied to a pharmaceutical preparation, tablet; and the results were compared with each other.

Cromatografia gasosa bidimensional abrangente (GC × GC)

This paper presents the fundamental principles, instrumentation and selected applications of comprehensive two-dimensional gas chromatography (GC × GC). In this technique, introduced in 1991, two capillary columns are coupled and proper modulating interfaces continuously collect the eluate from the first column, transferring it to the second column. The result is a geometric increment in the chromatographic resolution, ensuring separation of extremely complex mixtures in time periods shorter or comparable to those of analysis using conventional gas chromatography and with better detectabilities and sensitivities.

Eletrocromatografia capilar: contextualização, estado da arte e perspectivas

Capillary electrochromatography (CEC) is a separation technique in which the mobile phase flow is based on the application of a voltage across a packed capillary, which generates an electroosmotic flow that transports the analytes along the capillary toward the detector. As it combines the separation mechanisms of high-performance liquid chromatography (HPLC) and of capillary electrophoresis (CE), CEC can be considered a hybrid of HPLC and CE. This review presents some fundamental aspects of CEC and is focused on the instrumental advances of the technique, such as column technology, operation modes and detection systems, presenting recent papers on these topics and some applications and perspectives about CEC.