Edta como extractante universal : I- cationes mayores (Ca, Mg y K)

p.133-137Se escogieron 15 muestras de suelos de diferentes lugares del país procediéndose a la extracción de cationes mayores con solución 0,1 M de EDTA pH 7,0. Paralelamente las mismas muestras se trataron con solución de acetato de amonio pH 7,0, determinándose en ambas soluciones calcio, magnesio y potasio por espectro fotometría de absorción atómica. Los resultados analíticos indican una estrecha correlación para calcio, magnesio y potasio obtenidos con los dos extractantes

Edta como extractante universal : II parte, fósforo y elementos menores

p.139-144En la primera parte de este trabajo se estimó la factibilidad del uso de una solución de EDTA 0,1M en reemplazo de la tradicional de acetato de amonio 1M con el objeto de utilizarlo como extractante universal. En esta segunda parte, que debe tomarse como un intento preliminar, se prueba la extracción de fósforo y elementos menores. Se considera que los resultados son promisorios como primera aproximación para el fósforo, cobre, zinc y manganeso. Por ello se estima recomendable insistir en esta línea de trabajo que de lograr éxito permitirá agilizar los análisis químicos de suelo con el consiguiente incremento en la eficiencia de los laboratorios

Perempuan di persidangan : Pemantauan peradilan berperspektif perempuan

Jakartaxx, 234 p.; 21 c

Blending process modeling and control by multivariate curve resolution

The application of the Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) method to model and control blending processes of pharmaceutical formulations is assessed. Within the MCR-ALS framework, different data analysis approaches have been tested depending on the objective of the study, i.e., knowing the effect of different factors in the evolution of the blending process (modelling) or detecting the blending end-point and monitoring the concentration of the different species during and at the end of the process (control). Data analysis has been carried out studying multiple blending runs simultaneously taking advantage of the multiset mode of the MCR-ALS method. During the ALS optimization, natural constraints, such as non-negativity (spectral and concentration directions) have been applied for blending modelling. When blending control is the main purpose, a correlation constraint in the concentration direction has been additionally used. This constraint incorporates an internal calibration procedure, which relates resolved concentration values (in arbitrary units) with the real reference concentration values in the calibration samples (known references) providing values in real concentration scale in the final MCR-ALS results. Two systems consisting of pharmaceutical mixtures of an active principle (acetaminophen) with two or four excipients have been investigated. In the first case, MCR results allowed the description of the evolution of the individual compounds and the assessment of some physical effects in the blending process. In the second case, MCR analysis allowed the detection of the end-point of the process and the assessment of the effects linked to variations in the concentration level of the compounds.Peer reviewe

Blending process modeling and control by multivariate curve resolution

The application of the Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) method to model and control blend processes of pharmaceutical formulations is assessed. Within the MCR-ALS framework, different data analysis approaches have been tested depending on the objective of the study, i.e., knowing the effect of different factors in the evolution of the blending process (modeling) or detecting the blend end-point and monitoring the concentration of the different species during and at the end of the process (control). Data analysis has been carried out studying multiple blending runs simultaneously taking advantage of the multiset mode of the MCR-ALS method. During the ALS optimization, natural constraints, such as non-negativity (spectral and concentration directions) have been applied for blend modeling. When blending control is the main purpose, a variant of the MCR-ALS algorithm with correlation constraint in the concentration direction has been additionally used. This constraint incorporates an internal calibration procedure, which relates resolved concentration values (in arbitrary units) with the real reference concentration values in the calibration samples (known references) providing values in real concentration scale in the final MCR-ALS results. Two systems consisting of pharmaceutical mixtures of an active principle (acetaminophen) with two or four excipients have been investigated. In the first case, MCR results allowed the description of the evolution of the individual compounds and the assessment of some physical effects in the blending process. In the second case, MCR analysis allowed the detection of the end-point of the process and the assessment of the effects linked to variations in the concentration level of the compounds. © 2013 Elsevier B.V