Caracterização química do óleo da amêndoa de Sterculia striata St. Hil. et Naud

This paper describes total lipid content, unsaponifiable fraction and the acid, refractive, saponification and iodine indices of the oil of Sterculia striata nuts. The fatty acids, the sterols and the triterpene alcohols were determined. The percentage of cyclopropenoid fatty acids (CPFA), determined by NMR ¹H (15,5%), makes the nuts of this species unsuitable for human consumption.

Otimização dos parâmetros de extração para determinação multiresíduo de pesticidas em amostras de água empregando microextração em fase sólida

In this study the factors that affect the extraction of pesticide residues from water samples for their determination by solid-phase micro-extraction (SPME) and GC/MS were optimized. The fiber polymer, the extraction mode, the ionic strength, the stirring rate, the pH and the extraction time were the most significant parameters evaluated. The recovery obtained with the proposed method ranged from 94 to 110% and the sensitivity of the method, determined by calculating the detection limit (DL), ranged from 0.004 to 0.1 mug l-1. The results obtained with spiked real samples, at the 0.1 mug l-1 level, showed acceptable conformity with the expected values.

Extração de Al(III), Cr(III) e Fe(III) de meio etanólico usando o xerogel anilinapropilsílica

In this study, the preparation of the xerogel anilinepropylsilica is reported. The ability of the xerogel for extracting Al(III), Cr(III) and Fe(III) from ethanol was investigated at 25 ºC. The xerogel adsorption capacities were obtained from the adsorption isotherms by using the batch method. Flame atomic absorption spectrometry (FAAS) was used to estimate the concentration of metal ions in solution. The adsorption affinity follows the series Cr(III) > Fe(III) > Al(III) and the maximum adsorption capacities of the metal ions were 0.61, 0.52 and 0.43 mmol g-1, respectively.

Extração de pigmentos das sementes de Bixa orellana L.: uma alternativa para disciplinas experimentais de química orgânica

This paper describes methodologies for the extraction and characterization by TLC, UV-VIS, IR and NMR of bixin from Bixa orellana L. (urucum) seeds. Based on the results, the extraction with NaOH 5% is the fastest, uses low-cost materials, requires two to four laboratory hours and is a useful alternative for an experimental Organic Chemistry discipline.

Extração no ponto nuvem de compostos orgânicos homólogos e isômeros

In this work, the feasibility of employing micelle-mediated extraction for selective separation of homologous or isomeric organic compounds is demonstrated. Firstly, the main parameters controlling extraction performances, such as surfactant concentration and temperature were varied. A Scheffé-type experimental design was demonstrated as a novel and useful method to characterize the various experimental factors. At each point selected in the two-phase domain and for a given solute, extraction percentage (E%), concentration ratio, phase volume ratio, and equilibrium partition coefficient (K C) were determined. The values of E% and K C decrease in the following order: phenol > 1-phenylethanol ~ 2-phenylethanol > benzyl alcohol.

Ação adsorvente da bauxita sobre óleo isolante novo

Samples of new insulating mineral oil, after contact with bauxite, were analyzed by visible spectrophotometry, impedance spectroscopy and their total acidity index was measured. The results of these analyses were compared to samples of new insulating mineral oil, which had not been in contact with bauxite. The comparison demonstrated that the bauxite didn't reduce the insulating capacity of the mineral oil and thus could be used to treat the oil in situ during the operation of an electric transformer.

Otimização da reação de interesterificação química do óleo de palma

The Brazilian market has been showing a growing concern with nutritional values of oil components of foods. Chemical interesterification is a promising alternative to the current processes of modifying the consistency of oils. Chemical interesterification of deodorized palm oil was studied on a laboratory scale. The best results were obtained with 0.4% MeONa and heating for 20 min at 100 °C. These conditions are based on the largest variation in triacylglycerols as compared to a control. The trisaturated values varied from 6.2 to 9.9%, showing that the consistency of the oil improved for it to be used in margarines, without the formation of trans isomers.

Cromatografia de troca-iônica aplicada ao isolamento da fração ácida do óleo de copaíba (Copaifera multijuga) e da sacaca (Croton cajucara)

Plant extracts are usually complex mixtures which contain several molecules of different sizes with varied functional groups. Such extracts are a challenge to the chemist of natural products. Ion exchange chromatography in non-aqueous medium, used for separation of basic or acidic fractions from plant extracts, is an important unit operation in preparative scale separations. Anionic macroporous resin in non-aqueous medium was used with success in this study for separation of the acid fraction of Copaifera multijuga (Copaiba oil), rich in labdanic diterpenes and for the methanolic extract of Croton cajucara (acetyl aleuritoric acid).

Análise de praguicidas organofosforados em água por extração em fase sólida (SPE) utilizando discos C18 e cromatografia em fase gasosa: avaliação da contaminação do reservatório de Furnas (MG-Brasil)

Solid phase extraction (SPE) in C18 disks has been optimized and validated for extraction of 5 organophosphorus (OP) pesticides in water. Extraction has been followed by separation and detection by gas chromatography/flame photometry. Excellent linearity was obtained for all compounds (r greater than 0.99), with CVs between 1.0-6.9%, recoveries between 73-95% and quantification limits between 2.5-5.0 µg L-1. Samples from Furnas dam were analyzed monthly during one year and 10% showed OP pesticide residues.

Diazepam e nordiazepam em plasma: métodos de extração líquido-líquido e em fase sólida no pré-tratamento de amostras para análise cromatográfica em fase líquida

Analysis of diazepam (DZP) and its active metabolite nordiazepam (NDZP) in plasma is commonly performed in clinical medicine to ensure proper therapeutic effects while minimizing the incidence of toxicity. This study aimed to optimize analytical parameters and compare two pre-treatment techniques, liquid-liquid (LLE) and solid phase extraction (SPE), as well as liquid chromatographic conditions to analyze simultaneously DZP and NDZP in plasma from 20 patients treated with a daily dose of 10 mg. Both techniques showed to be well in line with the international criteria for analytical validation, which permitted to quantify DZP (66.2 - 1148.6 ng mL-1) and NDZP (138.5 - 808.6 ng mL -1) in all samples. The correlation coefficients between SPE and LLE were respectively 0.9729 for DZP and 0.9643 for NDZP.

Polímeros biomiméticos em química analítica. Parte 1: preparo e aplicações de MIP ("Molecularly Imprinted Polymers") em técnicas de extração e separação

MIPs are synthetic polymers that are used as biomimetic materials simulating the mechanism verified in natural entities such as antibodies and enzymes. Although MIPs have been successfully used as an outstanding tool for enhancing the selectivity or different analytical approaches, such as separation science and electrochemical and optical sensors, several parameters must be optimized during their synthesis. Therefore, the state-of-the-art of MIP production as well as the different polymerization methods are discussed. The potential selectivity of MIPs in the extraction and separation techniques focusing mainly on environmental, clinical and pharmaceutical samples as applications for analytical purposes is presented.

Avaliação do óleo essencial de Aloysia sellowii (Briquet) moldenke (Verbenaceae) do Sul do Brasil

This work was performed with the aim of evaluating the chemical variability among samples of Aloysia sellowii (Verbenaceae) collected in different geographical regions as well as the application of supercritical CO2 for obtaining essential oil. Thus, samples were collected in different localities and oils were isolated by hydrodistillation and supercritical CO2. Results showed existence of two chimiotypes in the species (cineole and sabinene). The supercritical CO2 extraction process was appropriate for extraction of A. sellowii essential oil at 40 ºC, 110 bar, 2 mL/min of flow and 10 min of extraction time.

Otimização do processo de extração e isolamento do antimalárico artemisinina a partir de Artemisia annua L.

Malaria is still one of the major diseases in the world, causing physical and economic problems in tropical regions. Artemisinin (Qinghaosu), a natural compound identified in Artemisia annua L. , is an effective drug mainly against cerebral malaria. The action of this drug is immediate and parasitaemia in the treatment of drug-resistant malaria is rapidily reduced, justifying the industrial production of artemisinin. This article focuses on the industrial production of this potent antimalarial drug, including strategies for enhancing yield using inexpensive and easy steps.

Uso do Blue Rayon para extração/concentração de compostos policíclicos em amostras ambientais

This is a review about the use of Blue rayon in the extraction and concentration of environmental contaminants in the aquatic environment. Blue rayon is an adsorbent composed of fibers covalently linked with copper phthalocyanine trisulphonate that has the ability to selectively adsorb polycyclic compounds. Blue rayon can be used in situ, in columns or in flasks. This method showed to be efficient in the extraction of important classes of environmental contaminants like the polycyclic aromatic hydrocarbons (PAHs), aromatic amines and phenylbenzotriazoles (PBTAs) and can be an important tool in monitoring studies for the evaluation of water quality.

Novos sorventes baseados em poli (metiloctilsiloxano) sobre sílica para uso em extração em fase sólida

This paper presents an easy and practical procedure to obtain silica-based C-8 type sorbents for use in solid-phase extraction. The materials are prepared by depositing poly(methyloctylsiloxane), PMOS, on the silica support. Two different treatments for immobilization were used: thermal treatment or gamma irradiation. Suitable recoveries were obtained after pre-concentration of dilute solutions, at the ng/L level, of a mixture of pesticides, indicating the good performance of the materials.