A feasible, rapid, sensitive and reliable dispersive liquid-liquid microextraction (DLLME) and ultrasonic assisted liquid-liquid microextraction (USAEME) combined with high-performance liquid chromatography (HPLC) method with UV detection was developed and validated for analysis of bosentan in human plasma and urine samples. All validation tests were reported according to FDA guidelines. Since chromatographic methods are precise, accurate and provide excellent separation are increasingly being used in determination of trace amount of drugs in biological goals. So the optimized experimental extraction factors from our previous work were used to evaluate HPLC-UV method for decreasing the limit of quantifications (LOQs) to cover the therapeutic range. Simple centrifugation of urine samples was sufficient prior to microextraction procedure, while acetonitrile protein precipitation provides sample clean up for plasma samples. The suggested method was linear (correlation coefficient R2 > 0.998) over a range of 0.1-10 µg mL-1 which covers the therapeutic range. Proposed methods are practical for quantitative analysis of bosentan in real samples, and could be used in routine clinical analyses.

En este artículo se calcularon los volúmenes molares y molares de exceso a partir de valores de densidad para los sistemas PEG 400 + agua y PEG 400 + etanol, en todo el intervalo de composición, a temperaturas entre 283,15 y 313,15 K. Los sistemas estudiados presentan volúmenes de exceso negativos probablemente debido a las fuertes interacciones por unión de hidrógeno entre las moléculas de los dos compuestos y a la gran diferencia en los volúmenes molares de los dos componentes puros. También se calcularon los coeficientes de expansión térmica-volumétrica en los solventes puros y las respectivas mezclas. Asimismo, se usó el modelo Jouyban- Acree para correlacionar la densidad y el volumen molar de las mezclas a las distintas temperaturas. Las desviaciones medias relativas en densidad fueron 0,1% y 0,5% para las mezclas acuosas y etanólicas, respectivamente, mientras que las desviaciones obtenidas para volumen molar fueron 18% y 6,9% para las mezclas acuosas y etanólicas, respectivamente. Los modelos obtenidos para las mezclas binarias con PEG 400 pueden usarse para predecir los valores con otros PEG, con un adecuado margen de error, utilizando las densidades de los solventes puros.

Molar volumes and excess molar volumes were investigated from density values for (PEG 400 + water) and (PEG 400 + ethanol) binary mixtures at temperatures from 283.15 K to 313.15 K. Both systems exhibit negative excess volumes probably due to increased interactions like hydrogen bonding and/or large differences in molar volumes of components. Volume thermal expansion coefficients were also calculated for binary mixtures and pure solvents. The Jouyban-Acree model was used for density and molar volume correlations of the studied mixtures at different temperatures. The mean relative deviations between experimental and calculated density data were 0.1 and 0.5 %, for aqueous and ethanolic mixtures, respectively; whereas, in molar volume data the values were 18.0 and 6.9 %, for aqueous and ethanolic mixtures, respectively. The trained versions of the model for PEG 400 binary solvents could be used to predict the density values of other PEGs with reasonable prediction error employing the density of mono-solvents.

En este trabajo se calcularon los volúmenes molares de exceso a partir de valores de densidad para los sistemas a) etanol + agua, b) 1,2-propanodiol + agua y c) etanol + 1,2-propanodiol, en todo el intervalo de composición, a temperaturas entre 278,15 y 288,15 K. Los volúmenes molares de exceso se modelaron de acuerdo a la ecuación de Redlich-Kister. Los sistemas estudiados presentan volúmenes de exceso altamente negativos probablemente debido a las fuertes interacciones por unión de hidrógeno entre las moléculas de los dos compuestos y a la gran diferencia en los volúmenes molares de los dos componentes puros. Finalmente se usó el modelo Jouyban-Acree para correlacionar la densidad y el volumen molar de las diferentes mezclas. Las desviaciones medias relativas en densidad fueron, 0,15, 0,08 y 0,01 %, para a), b) y c), respectivamente; mientras que el caso de volumen molar los valores fueron 1,9, 2,1 y 0,1 %, para a), b) y c), respectivamente.

Excess molar volumes and partial molar volumes were investigated from density values for a) ethanol (1) + water (2), b) 1,2-propanediol (1) + water (2), and c) ethanol (1) + 1,2-propanediol (2) mixtures, at temperatures from (278.15 to 288.15) K. Excess molar volumes were fitted by Redlich-Kister equation. The systems exhibit negative excess volumes probably due to increased interactions like hydrogen bonding and/or large differences in molar volumes of components. The Jouyban-Acree model was used for density and molar volume correlations of the studied mixtures at different temperatures. The mean relative deviations between experimental and calculated data in density data were 0.15, 0.08, and 0.01 %, for a), b), and c), respectively; whereas, in molar volume data the values were 1.9, 2.1, and 0.1 %, for a), b), and c), respectively.

Con ocasión del Año Internacional de la Química (2011) en este trabajo se realizó un análisis cienciométrico de los artículos publicados por científicos de Irán, Turquía, Egipto, Israel y Malasia en todos los campos investigativos y también en cuatro subcategorías de la química, según lo reportado en el sistema Scopus, a partir de lo cual, se discutieron varios aspectos cualitativos y cuantitativos sobre la producción académica. De acuerdo a lo obtenido, a nivel químico Irán es el líder entre los países evaluados en lo relacionado con el número de artículos publicados, mientras que Israel es el líder, seguido por Irán, al considerar los respectivos aspectos cualitativos de los autores y las publicaciones.

On the occasion of the International Year of Chemistry (2011), scientometric analysis of the publications of Iran, Turkey, Egypt, Israel and Malaysia in all fields and also in four chemistry sub-categories were extracted from Scopus and a number of quantitative and qualitative measures of the publications were discussed. Based on these findings, Iran is the leading state among the investigated countries in the field of chemistry concerning the number of publications and Israel is the leading state followed by Iran when the qualitative measures are considered.

Foi investigada a possibilidade de substituir os parâmetros de Abraham calculados teoricamente pelos parâmetros experimentais, na previsão da solubilidade de solutos não-aquoso em misturas de solventes binários, utilizando-se o modelo de Jouyban-Acree. As solubilidades de 90 conjuntos de dados, coletados a partir da literatura, foram preditas utilizando-se estes parâmetros, os coeficientes de solventes e também as solubilidades de sistemas mono-solventes. A precisão das solubilidades previstas foi avaliada calculando-se a média percentual do desvio (MPD) e também dos desvios percentuais (IPDs) individuais. O MPD global para a análise utilizando os parâmetros de Abraham, experimentais e teóricos, foram os mesmos e <14%. Uma boa distribuição (IPD) foi obtida por estas análises numéricas. Os conjuntos de dados investigados neste trabalho foram coletados a várias temperaturas e os resultados confirmaram a possibilidade de previsão da solubilidade em solventes binários a diferentes temperaturas. Explorou-se a possibilidade de cálculos ab initio nesta previsão utilizando as solubilidades calculadas em sistemas mono-solventes. No entanto, a diferença entre os valores previstos e observados, para os coeficientes dos solventes, aumentou para aproximadamente 60% e 200% quando usou-se gás e água, respectivamente. Estes, são valores muito grandes para várias aplicações de previsão.

The possibility of replacing theoretically computed Abraham parameters with the experimental Abraham parameters in solubility prediction of solutes in non-aqueous binary solvent mixtures using the Jouyban-Acree model was investigated. The solubilities of 90 data sets collected from the literature were predicted using their Abraham parameters, the solvent coefficients and also the solubilities in mono-solvent systems. The accuracy of the predicted solubilities was evaluated by calculating the mean percentage deviation (MPD) and also individual percentage deviations (IPDs). The overall MPD for the analysis using experimental and computed Abraham parameters were the same and was < 14%. A favoured IPD distribution was obtained for these numerical analyses. The data sets investigated in this work were collected at various temperatures and the results confirmed the possibility of solubility prediction in binary solvents at various temperatures. We did explore the possibility of ab initio solubility prediction of solutes in binary mixtures using the calculated solubilities in mono-solvent systems, however, the difference between the predicted and observed values increased to ca. 60% for gas-to-solvent coefficients and ca. 200% for water-to-solvent coefficients, which is too large for many predictive applications.