Scielo RSS <![CDATA[Eclética Química]]> http://www.scielo.br/rss.php?pid=0100-467020100003&lang=en vol. 35 num. 3 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[<b>Titrimetric and spectrophotometric assay of bupropion hydrochloride in pharmaceuticals using mercury(II) nitrate</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300001&lng=en&nrm=iso&tlng=en Two simple, rapid and accurate methods for the determination of bupropion hydrochloride (BUP) in pure and in pharmaceutical preparations are described. Both methods are based on the measurement of the chloride of its hydrochloride. In the titrimetric method, the chloride content of bupropion hydrochloride is determined by titrating with mercury(II)nitrate using diphenylcarbazone-bromophenol blue as indicator. Titrimetric method is applicable over a range 2-20 mg of BUP and the reaction stoichiometry is found to be 2:1 (BUP: Hg(NO3)2). The spectrophotometric method involves the addition of a measured excess of mercury(II) nitrate reagent in formate buffer to the drug, and after ensuring the reaction had gone to completion, the unreacted mercury(II) is treated with a fixed amount of diphenylcarbazone, and absorbance measured at 515 nm. The absorbance is found to decrease linearly with increasing concentration of BUP and the calibration curve is linear over 1.0-15.0 µg mL-1 BUP. The proposed methods were successfully applied to the determination of BUP in commercially available dosage forms with good accuracy and precision, and without detectable interference by excipients. The accuracy was further ascertained by placebo blank and synthetic mixture analyses and also by recovery experiments via standard-addition procedure. <![CDATA[<b>Biorremediação de solos contaminados por petróleo e seus derivados</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300002&lng=en&nrm=iso&tlng=en Em vista da eficiência comprovada da biorremediação na degradação de compostos tóxicos ao ser humano, como o benzeno, tolueno, etilbenzeno e xilenos (BTEX), diversas empresas, principalmente as relacionadas com consultorias e remediação ambiental, têm despertado grandes interesses pela implantação da biorremediação como opção para a reabilitação de áreas contaminadas. Em países desenvolvidos, como os Estados Unidos, Canadá e vários países da Europa, a técnica bioquímica de remediação vem sendo amplamente utilizada em trabalhos que se baseiam, por exemplo, no tratamento de solos contaminados por hidrocarbonetos de petróleo. Porém, ao contrário do que se tem notado nesses países, no Brasil, os projetos de biorremediação ainda estão no campo da teoria, com poucos casos práticos, embora exista uma probabilidade real de expansão. A esse despeito, uma das maiores pertinências dessa revisão é elucidar as vantagens que essa técnica pode oferecer quando é utilizada para a degradação de compostos, como os BTEX, em solos tipicamente brasileiros, cujas características físico-químicas contribuem, em muito, para a degradação desses contaminantes. Nessa conjuntura, pesquisas revelam que os fatores ambientais (como teores de umidade e oxigênio) e a disponibilidade de nutrientes nos solos, além das condições climáticas do Brasil, são bastante adequadas para o emprego dessa técnica. Isso pode trazer como vantagens, ótima relação custo-benefício e maior eficiência na degradação de compostos tóxicos e recalcitrantes frente à maioria das técnicas convencionais de remediação. Em síntese, a presente revisão busca enfocar o estado da arte das técnicas de biorremediação de contaminantes em solos, apresentando as mais atuais e recentes aplicações e inovações, tanto no âmbito nacional quanto no internacional.<hr/>In view of the proven efficiency of bioremediation in the degradation of compounds toxic to humans, such as benzene, toluene, ethylbenzene and xylenes (BTEX), several companies, especially those related to remediation and environmental monitoring, have shown enormous interest in the deployment of bioremediation as an option for the rehabilitation of contaminated areas. In developed countries such as the United States, Canada and several European countries, these biochemical remediation techniques have been widely used in work that is based, for example, on the treatment of soil contaminated by petroleum hydrocarbons. However, contrary to what has been done in these countries, in Brazil, bioremediation projects are still mainly theoretical, with few practical cases, but there is a real likelihood of expansion. The more important aim of this review is to indicate the advantages that this technique can offer when it is used for the degradation of compounds such as BTEX in typical Brazilian soils, whose physico-chemical characteristics contribute to the degradation of contaminants. Research shows that environmental factors (such as moisture and oxygen levels) and the availability of soil nutrients, in addition to the climatic conditions in Brazil, are quite suitable for the employment of this technique. They may pose, as an advantage, a favorable cost/benefit ratio and the opportunity for greater efficiency in the degradation of toxic and recalcitrant compounds compared to the majority of conventional remediation techniques. In summary, this review focuses on the state of the art of bioremediation techniques of contaminants in soils, presenting the most current and recent applications and innovations, as reported in the national and international media. <![CDATA[<b>Development and validation of spectrophotometric method for the determination of DPP-4 inhibitor, sitagliptin, in its pharmaceutical preparations</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300003&lng=en&nrm=iso&tlng=en A simple, sensitive and reproducible spectrophotometric method was developed for the determination of sitagliptin phosphate in bulk and in pharmaceutical formulations. The proposed method is based on condensation of the primary amino group of sitagliptin phosphate with acetyl acetone and formaldehyde producing a yellow colored product, which is measured spectrophotometrically at 430nm. The color was stable for about 1 hour. Beer's law is obeyed over a concentration range of 5-25 µg/ml. The apparent molar absorptivity and Sandell sensitivity values are 1.067 x 10(4) Lmol-1cm-1 and 0.0471 µgcm-2 respectively. All the variables were studied to optimize the reaction conditions. No interference was observed in the presence of common pharmaceutical excipients. The validity of the method was tested by analyzing sitagliptin phosphate in its pharmaceutical preparations. Good recoveries were obtained. The developed method was successfully employed for the determination of sitagliptin phosphate in various pharmaceutical preparations. <![CDATA[<b>Viabilidade do emprego de ácido fluorídrico 10% para a remoção de íons paramagnéticos em amostras de solos e suas respectivas frações físicas</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300004&lng=en&nrm=iso&tlng=en A utilização de efluentes de esgoto tratado na irrigação, ao invés de realizar a disposição deste subproduto nos cursos d'água tem sido uma alternativa antiga, popular e atrativa, com triplo propósito: tratamento complementar do efluente, fonte de água e de nutrientes ao sistema solo-planta. Entretanto, no Brasil, há falta de tradição na reciclagem de águas residuárias, particularmente, do efluente de esgoto tratado e, conseqüentemente, poucos têm sido as pesquisas relacionadas a este tema. Com a finalidade de fornecer mais informações para subsidiar as pesquisas nesta área, este trabalho visa avaliar, por meio de técnicas químicas e espectroscopias, o processo de humificação na matéria orgânica dos solos irrigados com efluente de esgoto tratado em experimentos de campo. Os cinco tratamentos estudados foram: TSI (controle) - irrigado com água potável e adição de nitrogênio via fertilizante mineral, T100, T125, T150 e T200 irrigado com efluente de esgoto tratado e adição de nitrogênio via fertilizante mineral. Os resultados obtidos mostram variações no teor de carbono e no grau de humificação, para os solos irrigados com efluente de esgoto tratado, decorrentes do aumento da atividade de decomposição da matéria orgânica, estimulada pelo aumento de água no solo.<hr/>Treated sewage effluent utilization for irrigation represents an antique, popular and attractive alternative to the common disposal of effluent to watercourses and includes three main purposes: effluent complementary treatment, water and nutrient source to the soil-plant system. However, because in Brazil no experiences in wastewater recycling exists consequently few scientific studies were carried out despite the importance of the subject. The present study aimed to evaluate by chemical and spectroscopy techniques the soil organic matter from soils irrigated with treated sewage effluent. Five treatments were evaluated: TSI (control) irrigation with potable water and addition of the nitrogen as mineral fertilizer; T100, T125, T150 and T200 - irrigation with treated sewage sludge effluent and addition of the nitrogen as mineral fertilizer. The results obtained shown changes in the carbon contend and humification degree for the soils irrigated with treated sewage sludge effluent due to the increase activity of the decomposition of organic matter, stimulated by the increase of water in the soil. <![CDATA[<b>Estudo preliminar do vermicomposto produzido a partir de lodo de esgoto doméstico e solo</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300005&lng=en&nrm=iso&tlng=en O lodo de esgoto doméstico é um resíduo gerado durante os processos de tratamento de esgoto, podendo ser estabilizado por diversos processos químicos, físicos e biológicos. O lodo de esgoto estabilizado (biossólido) não possui um destino final adequado e gera diversos problemas no sentido de sua disposição final. Dentre os muitos processos que visam à disposição do biossólido, destaca-se a reciclagem agrícola. A utilização da vermicompostagem como meio de estabilização do lodo de esgoto mostra-se como uma ferramenta útil na estabilização deste resíduo. O processo de vermicompostagem apresentou características físico-químicas satisfatórias para ser utilizado como técnica de estabilização do lodo de esgoto doméstico. O produto final apresentou potencial para ser utilizado na agricultura como fertilizante ou condicionador de solos.<hr/>Domestic waste, a residue generated during sewage treatments, can be stabilized by many chemical, physical and biological processes. However, the stabilized waste (biosoil) currently lacks proper disposal alternatives. A new and promising disposal method is called farm recycling. The use of vermicomposting has shown to be useful as a mean to stabilize domestic waste. The biosoil achieved through this method exhibits high humidity-retaining capacity, good C/N relationship, as well as a satisfactory percentage of humic acid, thus being able to be incorporated into the soil as a conditioner and fertilizer. <![CDATA[<b>Características físico-químicas de ácidos húmicos em diferentes etapas da vermicompostagem</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300006&lng=en&nrm=iso&tlng=en Amostras de materiais coletados em diferentes estádios de vermicompostagem foram submetidas a procedimentos de extração de ácidos húmicos. Técnicas de titulação potenciométrica, termogravimetria (DTG), difração de raios X e espectrofotometria no uv/visível e no infravermelho foram utilizadas no estudo desses materiais. Os dados de titulação foram submetidos ao ajuste por regressão não-linear, determinando-se, assim, cinco valores de pKa característicos de cinco classes de grupos tituláveis. Nas curvas DTG, foram observadas duas etapas, sendo a primeira característica da separação de estruturas alifáticas e, ou, alicíclicas e a segunda, a decomposição de estruturas aromáticas. A difratometria de raios X apresentou diferenças marcantes nos resultados, principalmente nos três primeiros picos onde parecem ocorrer reorganização estrutural e polimerização ao longo do processo de vermicompostagem. Os espectros do infravermelho não apresentaram diferenciação entre os espectros. Os valores da razão E4/E6 encontrados estão de acordo com os característicos dos ácidos húmicos, mas não fornecem informações que possam contribuir para a elucidação da estrutura e formação desses ácidos.<hr/>Samples of materials, collected at different stages of vermicompostaging, were submitted to extraction procedures of humic acids. Titration, termogravimetry (DTG), X-ray diffraction, spectrophotometry in the uv/visible and infrared techniques, were used in the study of these materials. The data from the potentiometry titration analysis were submitted to adjustment by non-linear regression, determining thus five values of pKa's characteristic of five classes of titrable groups. In the DTG curves two stages can be observed, being the first one characteristic of the separation of aliphatic and/or alycyclic structures and the second of decomposition of aromatic structures. The X-ray diffraction technique exhibed marked differences in the results, mainly in the first three peaks, were a structural reorganization and a polymerization along the vermicompostaging process. The infrared spectra practically no differentiation between the samples. The values for the ratio E4/E6 found are in accordance with the characteristic values for humic acids, but do not supply information that can contribute to the elucidation of the structure and formation of these acids. <![CDATA[<b>Estimation of standard enthalpy of formation of alkanes in gaseous state by calculating size, structural and electronic parameters in the molecules</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300007&lng=en&nrm=iso&tlng=en A quantitative analysis is made on the correlation ship of thermodynamic property, i.e., standard enthalpy of formation (ΔH fº) with Kier's molecular connectivity index(¹Xv),vander waal's volume (Vw) electrotopological state index (E) and refractotopological state index (R) in gaseous state of alkanes. The regression analysis reveals a significant linear correlation of standard enthalpy of formation (ΔH fº) with ¹Xv, Vw, E and R. The equations obtained by regression analysis may be used to estimate standard enthalpy of formation (ΔH fº) of alkanes in gaseous state. <![CDATA[<b>Spectrophotometric determination of nevirapine using tetrathiocyanatocobalt(II) ion as a reagent</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300008&lng=en&nrm=iso&tlng=en A simple and rapid spectrophotometric method for the determination of nevirapine is described. The method is based on the reaction of nevirapine with tetrathiocyanatocobalt(II) ion in buffer of pH 4 to form the corresponding complex. Beer's law is obeyed in the range of 0.2 - 2.0 µg mL-1 for nevirapine. The optical parameters such as molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit were found to be 1.16× 10(4) Lmol-1cm-1, 2.09 X 10-3 µg cm-2, 0.073 µg mL-1 and 0.222 µg mL-1 respectively. The optimum reaction conditions and other analytical parameters were evaluated. The statistical evaluation of the method was examined by determining intra-day and inter-day precision. The proposed method has been successfully applied for the determination of nevirapine in pharmaceutical formulations. <![CDATA[<b>Bound state solutions of schrödinger equation for a more general exponential screened coulomb potential via Nikiforov-Uvarov method</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300009&lng=en&nrm=iso&tlng=en The arbitrary angular momentum solutions of the Schrödinger equation for a diatomic molecule with the general exponential screened coulomb potential of the form V(r) = (- a / r){1+ (1+ b )e-2b } has been presented. The energy eigenvalues and the corresponding eigenfunctions are calculated analytically by the use of Nikiforov-Uvarov (NU) method which is related to the solutions in terms of Jacobi polynomials. The bounded state eigenvalues are calculated numerically for the 1s state of N2 CO and NO <![CDATA[<b>New reagents for the spectrophotometric determination of ranitidine hydrochloride</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300010&lng=en&nrm=iso&tlng=en A new spectrophotometric method is proposed for the assay of ranitidine hydrochloride (RNH) in bulk drug and in its dosage forms using ceric ammonium sulphate (CAS) and two dyes, malachite (MAG) green and crystal violet (CV) as reagents. The method involves the addition of a known excess of ceric ammonium sulphate to ranitidine hydrochloride in acid medium, followed by the determination of unreacted CAS by reacting with a fixed amount of malachite green or crystal violet and measuring the absorbance at 615 or 582 nm respectively against the reagent blank. The Beer's law is obeyed in the concentration range of 0.4-8.0 µg/ ml of ranitidine hydrochloride (RNH) for RNH-MAG system and 0.2-1.6µg/ml of ranitidine hydrochloride for RNH-CV system. The molar Absorptivity, Sandell's sensitivity for each system were calculated. The method has been successfully applied to the determination of ranitidine hydrochloride in pure and dosage forms. <![CDATA[<b>Avaliação da qualidade das águas do Rio São Francisco Falso, tributário do reservatório de Itaipu, Paraná</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300011&lng=en&nrm=iso&tlng=en uma avaliação do impacto das espécies do nitrogênio e do fósforo foi conduzida nas águas do Rio São Francisco Falso, afluente do Reservatório de Itaipu. Os resultados de quatro campanhas revelam que o estado trófico destas águas oscila de oligotróficas a mesotróficos, sendo que o ultimo estado foi observado em campanhas sobre influência de chuvas. Das espécies do nitrogênio, o NO2 apresentou valores acima dos recomendados pela agência ambiental canadense, representando um risco à vida aquática. Em comparação ao Rio Ocoí, outro afluente do Reservatório de Itaipu, as águas do Rio São Francisco Falso apresentam melhor qualidade.<hr/>an environmental assessment about phosphorus and nitrogen species was carried out in waters of São Francisco Falso River, tributary of Itaipu Reservoir. Results from four field campaigns showed that trophic state vary of oligotrophic to mesotrophic, being the latter observed under rain influence. Among nitrogen species, NO2 presented concentration above guide-value recommended by Canadian environmental agency, what means a risk for aquatic life. In comparison to Ocoí River, another tributary of Itaipu Reservoir, São Francisco's waters showed better quality. <![CDATA[<b>Development and validation of spectroscopic methods for simultaneous estimation and dissolution of ofloxacin and ornidazole in tablet dosage forms</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300012&lng=en&nrm=iso&tlng=en The aim of this work was to develop and validate simple, accurate and precise spectroscopic methods (multicomponent, dual wavelength and simultaneous equations) for the simultaneous estimation and dissolution testing of ofloxacin and ornidazole tablet dosage forms. The medium of dissolution used was 900 ml of 0.01N HCl, using a paddle apparatus at a stirring rate of 50 rpm. The drug release was evaluated by developed and validated spectroscopic methods. Ofloxacin and ornidazole showed 293.4 and 319.6nm as λmax in 0.01N HCl. The methods were validated to meet requirements for a global regulatory filing. The validation included linearity, precision and accuracy. In addition, recovery studies and dissolution studies of three different tablets were compared and the results obtained show no significant difference among products. <![CDATA[<b>Determinação colorimétrica de metabissulfito</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300013&lng=en&nrm=iso&tlng=en O ânion metabissulfito é largamente usado como agente anti-oxidante e preservativo de uma variedade de produtos industrializados. A interação desta espécie com o corante pararosanilina é capaz de promover o rebaixamento da banda de absorção do pigmento na região do visível. Utilizando as melhores condições experimentais, tais como, solução tampão Britton e Robinson, pH 5,0 e corante em 1,0x10-4 mol L-1, foi possível obter uma relação entre concentração de metabissulfito e absorbância, na faixa entre 1,3x10-6 mol L-1 a 3,0x10-5 mol L-1. O limite de detecção foi calculado em 5,0x10-7 mol L-1. A metodologia foi aplicada em amostras reais.<hr/>Metabisulfite anion is widely used as an antioxidant agent and preservative of a number of industrialized products. The interaction of this agent with pararosaniline dye can reduce the absorption band of the pigment within the visible area. From the best experimental conditions such as Britton-Robinson buffer solution, pH 5.0, and dye in a solution of 1.0x10-4 mol L-1, it was possible to obtain a relation between concentration of metabisulfite and absorbance in a range from 1,3x10-6 mol L-1 to 3.0x10-5 mol L-1. The detection limit was calculated in 5.0x10-7 mol L-1. The methodology was applied on real samples. <![CDATA[<b>Permeabilidade e autoindução magnética do níquel e da platina em função da temperatura</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300014&lng=en&nrm=iso&tlng=en Efeito da temperatura sobre a autoindução magnética do níquel e da platina e a permeabilidade magnética do níquel, no intervalo de temperatura de 525K a 620K, confirma dados encontrados na literatura.<hr/>Effect of temperature on the magnetic permeability and magnetic self induction of Nickel and Platinum in the range 525K-620K. <![CDATA[<b>Monitoramento do corante pararosanilina em amostras biológicas</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300015&lng=en&nrm=iso&tlng=en O corante pararosanilina (P) é um pigmento que apresenta um relevante papel na análise de substâncias química e bactérias do tipo Gram positivo e negativo, além de outros microorganismos. Os ensaios potenciométricos de P mostraram que o corante é um ácido monoprótico e fraco (pKa= 8,78); enquanto a espectrofotometria permitiu estimar seu coeficiente de absortividade molar (ε) igual a 1,48x10(4) mol-1 cm-1 L. A curva analítica para a determinação de P apresenta linearidade entre 7,36x10-6 a 7,36x10-5 mol L-1 e a metodologia foi aplicação em amostras biológicas.<hr/>Pararosaniline dye (P) is a pigment which has a significant role in analysis of chemical substances and gram-positive and negative bacteria, as well as other microorganisms. Potentiometric essays of P have shown that the colorant is a weak monoprotic acid (pKa= 8,78); and the spectrophotometry allows to estimate its molar absorption coefficient as 1,48x10(4) mol-1 cm-1 L. The analytical curve for a determination of P has linearity between 7,36x10-6 and 7,36x10-5 mol L-1, and the methodology was application in biological samples. <![CDATA[<b>Avaliação espectrofotométrica das formas CR<sup>+3</sup>, CRO<sub>4</sub><sup>-2</sup> e CR<sub>2</sub>O<sub>7</sub><sup>-2</sup></b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300016&lng=en&nrm=iso&tlng=en Um estudo espectrofotométrico de especiação das formas Cr+3, CrO4-2 e Cr2O7-2 foi realizado em amplo intervalo de pH de 2,0 a 12,0 em solução tampão Britton-Robinson. Os espectros de absorção das regiões ultra-violeta e visível são bem caracterizados, apresentando bandas nas duas regiões espectrais. A relação de absorbância versus concentração, para cada espécie química, permitiu conhecer o coeficiente de absortividade molar das entidades químicas.<hr/>A spectrophometric study of the speciation of the chemical forms Cr+3, CrO4-2 and Cr2O7-2 was carried out on a wide interval of pH (from 2,0 to 12,0) in a Britton-Robinson buffer solution. The absorption spectra of the ultraviolet and visible regions are well defined and show bands in the two spectral regions. The relation between absorbance versus concentration for each chemical species allowed us to know the molar absorption coefficients of the chemical entities. <![CDATA[<b>Chemical indexes calculated for 8,11,13-trien-abietane diterpenoids isolated from <i>Swartzia </i>species</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300017&lng=en&nrm=iso&tlng=en The disparity found in the molecular structures of compounds isolated from nine plants of the Swartzia genus indicates that the Swartzia species that furnished cassane diterpenoids and triterpenoidal saponins are more recent, since these metabolites have adopted the mevalonic acid route of formation, abandoning the shikimic acid/acetate route that produces the isoflavonoids found in the remaining species. Chemical indexes calculated from the molecular structure diversities of sixteen 8,11,13-trien-abietane diterpenoids isolated from Swartzia langsdorffii and S. arborescens indicate that S. arborescens is more recent than S. langsdorffii. The results suggest a more evolved position in Swartzia species of the section Possira.<hr/>A análise das estruturas moleculares dos compostos isolados de nove plantas do gênero Swartzia mostrou que, na produção de metabólitos especiais, algumas plantas abandonaram a rota do ácido shikimic/acetato e adotaram a rota do ácido mevalônico. Esta mudança é fator indicativo de que essas espécies são evolutivamente mais recentes. Já a diversidade de estruturas moleculares encontrada nos dezesseis diterpenoides 8,11,13-trien-abietanos, chamados de swartziarboreols, identificados em S. arborescens e S. langsdorffii, permitiu atribuir a cada uma dessas espécies um índice químico, mostrando que os de S. arborescens são mais recentes do que os de S. langsdorffii. Os resultados sugerem que as espécies da seção Possira devam ocupar uma posição derivada em Swartzia. <![CDATA[<b>A simple spectrophotometric method for the determination of captopril in pharmaceutical preparations using ammonium molybdate</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300018&lng=en&nrm=iso&tlng=en A simple, rapid and sensitive spectrophotometric method for the determination of captopril (CPT) in pharmaceutical formulations is proposed. This method is based on the reduction reaction of ammonium molybdate, in the presence of sulphuric acid, for the group thiol of CPT, producing a green compound (λ max 407 nm). Beer's law is obeyed in a concentration range of 4.60 x 10-4 - 1.84 x 10-3 mol l-1 of CPT with an excellent correlation coefficient (r = 0.9995). The limit of detection and limit of quantification were 7.31 x 10-6 e 2.43 x 10-5 mol l-1 of CPT, respectively. The proposed method was successfully applied to the determination of CPT in commercial brands of pharmaceuticals. No interferences were observed from the common excipients in the formulations. The results obtained by the proposed method were favorably compared with those given by the official reported method at 95 % confidence level.<hr/>Um método simples, rápido e sensível para a determinação espectrofotométrica de captopril (CPT) em formulações farmacêuticas é proposto. Este método é baseado na reação de redução do molibdato de amônio, na presença de ácido sulfúrico, pelo grupo tiol do CPT, produzindo um composto verde (λ max 407 nm). A lei de Beer é obedecida na faixa de concentração de 4,60 x 10-4 a 1,84 x 10-3 mol L-1 de CPT com um excelente coeficiente de correlação (r = 0,9995). O limite de detecção e o limite de quantificação foram de 7,31 x 10-6 e 2,43 x 10-5 mol L-1 de CPT, respectivamente. O método proposto foi aplicado com sucesso na determinação da CPT em amostras comerciais de produtos farmacêuticos. Não foram observadas interferências dos excipientes comumente encontrados nas formulações farmacêuticas. Os resultados obtidos pelo método proposto foram comparados favoravelmente com aqueles obtidos pelo método oficial relatado em um nível de 95% de confiança. <![CDATA[<b>Análise de pesticidas organoclorados em óleos vegetais por cromatografia gasosa de alta resolução (HRGC)</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300019&lng=en&nrm=iso&tlng=en Os óleos vegetais comestíveis foram introduzidos na dieta humana em substituição as gorduras animais nas últimas décadas sendo amplamente consumidos em todo o mundo. O presente artigo descreve o desenvolvimento de uma metodologia para análise de aldrin, dieldrin, endrin e endosulfan em óleos vegetais por cromatografia gasosa de alta resolução (HRGC) utilizando-se extração em fase sólida (SPE). As médias de recuperação dos pesticidas estiveram entre 70 e 110%[1].<hr/>Vegetable oil were introduced in human diet in the last decade to change the use of animal fats. The chemical products althrought utilized in correct manner can cause residues in food bring to healt there be a necessity of a constant monitoring of the concentration level the several agricultural products. The answer to this necessity has motivated the development of several of a methodology for simultaneous analysis of aldrin, dieldrin, endrin and endosulfan in vegetable oils by HRGC, using solid phase extraction (SPE) using silica and XAD-2. The recovery was 70-110% <![CDATA[<b>Adsorption isotherm studies of BOD, TSS and colour reduction from palm oil mill effluent (POME) using boiler fly ash</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-46702010000300020&lng=en&nrm=iso&tlng=en Palm oil is one of the two most important vegetable oils in the world's oil and fats market. The extraction and purification processes generate different kinds of waste generally known as palm oil mill effluent (POME). Earlier studies had indicated the possibility of using boiler fly ash to adsorb impurities and colour in POME treatment. The adsorption treatment of POME using boiler fly ash was further investigated in detail in this work with regards to the reduction of BOD, colour and TSS from palm oil mill effluent. The amount of BOD, colour and TSS adsorbed increased as the weight of the boiler fly ash used was increased. Also, the smaller particle size of 425µm adsorbed more than the 850µm size. Attempts were made to fit the experimental data with the Freundlich, Langmuir and Dubinin-Radushkevich isotherms. The R² values, which ranged from 0.8974-0.9898, 0.8848-0.9824 and 0.6235-0.9101 for Freundlich, Langmuir and Dubinin-Radushkevich isotherms respectively, showed that Freundlich isotherm gave a better fit followed by Langmuir and then Dubinin-Radushkevich isotherm. The sorption trend could be put as BOD > Colour > TSS. The apparent energy of adsorption was found to be 1.25, 0.58 and 0.97 (KJ/mol) for BOD, colour and TSS respectively, showing that sorption process occurs by physiosorption. Therefore, boiler fly ash is capable of reducing BOD, Colour and TSS from POME and hence could be used to develop a good adsorbent for POME treatment.