Abstract Molecularly imprinted polymers (MIPs) are an important class of compounds with wider sensing applications for the determination of substances ranging from small molecular masses to macro size. The hyphenation of MIP principle with other likewise conducting polymers yields the devices for sensing purposes. MIPs are robust against environmental conditions, more economical than natural receptors, and their preparation is also adequate for substances without natural receptors. Organic mediated MIPs compounds are of current interest, due to their applicability as quantification tools to determine electroactive substances in a variety of real samples. MIPs are highly selective for target molecules, mechanically strong, resistant to temperature and pressure, inert towards acids, bases, metal ions and organic solvents, highly stable for longer periods, and operative at room-temperature. Therefore, during past years, MIPs have been used as electrochemical and optical sensors, sorbents, solid phase media, and so on. Herein, there is a focus on the use of Pyrrole (Py) as a monomeric molecule to fabricate MIPs. Py or poly-Py (p-Py) based MIPs are synthesized and used in various capacities as chemo electrochemical sensors. A detailed discussion on the application of Py-mediated MIPs for the electrochemical determination of some organic compounds of therapeutic and environmental interest is herein presented as a review.

Hydroxyzine dihydrochloride (HDH), a piperazine H1-receptor antagonist and antihistamine, is a rapid acting anxiolytic used principally as an antiemetic. A sensitive, selective, and precise and accurate spectrophotometric method based on the formation of an ion-pair with orange II (ORG II) as ion-pair complexing agent was developed and validated for the determination of HDH in pharmaceuticals. The chloroform-extractable ion-pair complex exhibited an absorption maximum at 480 nm. Optimization of different experimental conditions is described. Beer's law is obeyed in the range of 1.5-15 μg mL-1 with an apparent molar absorptivity value of 2.07 × 10(4) L mol-1 cm-1 and Sandell's sensitivity value of 0.0216 μg cm-2. The limit of detection (LOD) and limit of quantification (LOQ) are 0.14 and 0.41 μg mL-1, respectively. A Job's plot of absorbance versus molar ratio of HDH to ORG II indicated (1:2) stoichiometric ratio. Within-and between-day relative standard deviations at three different concentration levels were < 3%. The developed method was successfully applied to commercial tablets. The results obtained were in good agreement with those obtained using the official method. No interference was encountered from coformulated substances. Recoveries were 96-109 %.

El dihidrocloruro de hidroxicina (HDH), una piperazina antagonista del receptor H1 y un antihistamínico, es un ansiolítico de acción rápida usado principalmente como anti-emético. Se desarrolló y validó un método espectrofotométrico sensible, selectivo, preciso y exacto basado en la formación de un par iónico con naranja II (ORG II) como un agente complejante para la determinación de HDH en productos farmacéuticos. El par iónico extraído en cloroformo exhibió un máximo de absorción a 480 nm. Se describió la optimización de las diferentes condiciones experimentales. La ley de Beer se obedeció en el intervalo de 1.5-15 μg mL-1 con un valor de absortividad molar aparente de 2.07 × 10(4) L mol-1 cm-1 y un valor de sensibilidad de Sandell de 0.0216 μg cm-2. El límite de detección (LD) y el límite de cuantificación (LC) son 0.14 y 0.41 μg mL-1, respectivamente. Una gráfica de Job de absorbancia versus relación molar de HDH y ORG II indicó una relación estequiométrica (1:2). Las desviaciones estándar relativas dentro y entre días, a tres diferentes niveles de concentración, fueron < 3%. El método desarrollado fue aplicado exitosamente a tabletas comerciales. Los resultados obtenidos estuvieron en buena concordancia con los obtenidos con el método oficial. No se encontró ninguna interferencia de parte de las sustancias de la formulación. Las recuperaciones fueron de 96-109 %.

Dois métodos espectrofotométricos novos, usando o permanganato como o reagente oxidimétrico para a determinação da olanzapina (OLP) foram utilizados e validados de acordo com as diretrizes atuais do ICH. Os métodos envolveram a adição de excesso conhecido de permanganato à OLP em meio ácido ou alcalino, determinando-se o permanganato que não reagiu em 550 nm (método A), ou pela cor verde-azulada do manganato a 610 nm (método B). A diminuição da absorbância no método A ou o aumento da absorbância no método B, em função da concentração de OLP, foi medida e relacionada à concentração de OLP. Sob condições otimizadas, a lei de Beer foi obedecida, nas faixas de concentração de 2,0 a 20 e 1,0 a 10 ao μg mL-1, no método A e no método B, respectivamente. Os valores de absortividade molar foram de 1,34 x 104 e 2,54 x 104 l mol-1cm-1 para o método A e para o método B, respectivamente, e as sensibilidades respectivas de Sandell foram de 0,0233 e 0,0123 μg cm-2. Os LOD e os LOQ para o método A calculados foram 0,37 e 1,13 μg mL-1e os valores correspondentes para o método B foram 0,16 e 0,48 μg mL-1. A precisão intermediária, expressa como RSD, encontrou-se na faixa de 0,51 a 2,66%, e a exatidão, expressa como o erro relativo, variou de 0,79 a 2,24%. Os métodos propostos foram aplicados com sucesso ao ensaio de OLP em comprimidos comerciais, com porcentagens médias de recuperação de 102± 1,59% (método A) e de 101± 1,53% (método B). A exatidão e a confiabilidade dos métodos foram confirmadas executando testes de recuperação através de procedimento padrão de adição.

Two new spectrophotometric methods using permanganate as the oxidimetric reagent for the determination of olanzapine (OLP) were developed and validated as per the current ICH guidelines. The methods involved the addition of known excess of permanganate to OLP in either acid or alkaline medium followed by the determination of unreacted permanganate at 550 nm (method A) or bluish-green color of manganate at 610 nm (method B). The decrease in absorbance in method A or increase in absorbance in method B as a function of concentration of OLP was measured and related to OLP concentration. Under optimized conditions, Beer's law was obeyed over the ranges 2.0 to 20 and 1.0 to 10 μg mL-1 in method A and method B, respectively. The calculated molar absorptivity values were 1.34 x 10(4) and 2.54 x 10(4) l mol-1cm-1 for method A and method B respectively, and the respective Sandell sensitivities were 0.0233 and 0.0123 μg cm-2. The LOD and LOQ for method A were calculated to be 0.37 and 1.13 μg mL-1and the corresponding values for method B were 0.16 and 0.48 μg mL-1. Intermediate precision, expressed as RSD was in the range 0.51 to 2.66 %, and accuracy, expressed as relative error ranged from 0.79 to 2.24 %. The proposed methods were successfully applied to the assay of OLP in commercial tablets with mean percentage recoveries of 102 ±1.59 % (method A) and 101 ±1.53 % (method B). The accuracy and reliability of the methods were further confirmed by performing recovery tests via standard addition procedure.

Abstract Titrimetric and spectrophotometric assay of pantoprazole sodium (PPS) using permanganate as the oxidimetric reagent is described. In titrimetry, PPS is treated with a measured excess of permanganate in H2SO4 medium followed by the determination of unreacted oxidant by back titrating with a standard iron(II) solution. Spectrophotometry involves addition of a known excess of permanganate to PPS in H2SO4 medium followed by the measurement of absorbance of the residual permanganate at 545 nm. In both the methods, the amount of permanganate reacted corresponds to the PPS content. Experimental conditions that provide wide linear range, maximum sensitivity and selectivity, and accuracy and precisions have been optimized. In titrimetry, the calculations are based on a 1:1 (PPS : KMnO4) reaction stoichiometry and the method is applicable over 1.0-7.0 mg range. In spectrophotometry, Beer's law is obeyed over the concentration range 15.0-150.0 µg mL-1. The linear regression equation of the calibration graph is A = 0.78 + 0.005 C with a regression coefficient (r) of 0.9982 (n = 11). The apparent molar absorptivity is calculated to be 2.213 × 10³ l mol-1cm-1 and the Sandell sensitivity is 0.1954 µg cm-2. The limits of detection (LOD) and quantification (LOQ) calculated as per the ICH guidelines are 0.73 and 2.21 µg mL-1, respectively. Accuracy and precision of the assays were determined by computing the intra-day and inter-day variations at three different levels of PPS; the intra-day and inter-day RSD was < 3.09 % and the accuracy was better than 3.5 %. The methods were successfully applied to the determination of PPS in three different brands of tablets 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.

En este trabajo se describe la cuantificación de pantoprazol sódico (PPS) mediante una valoración redox usando permanganato como agente oxidante siguiendo la determinación potenciométrica y espectrofotométricamente. En potenciometría, se adiciona un exceso de permanganato en medio H2SO4 y el PPS es cuantificado valorando el excedente de permanganato con una solución estándar de Fe(II). La determinación espectrofotométrica se realiza agregando permanganato a una concentración que asegure un exceso conocido y se mide la absorbancia del permanganato residual a 545 nm. En ambos métodos la cantidad de permanganato que reacciona con PPS esta relacionada con el contenido de PPS. Fueron optimizadas las condiciones experimentales que proporcionan un rango lineal, selectividad y sensibilidad máxima, precisión y exactitud. En potenciometría, los cálculos se basan en una estequiométrica de reacción 1:1 (PPS: KMnO4) y el método es aplicable en un intervalo de 1.0-7.0 mg. En espectrofotometría, la ley de Beer es lineal en un intervalo de concentración de 15.0-150.0 µg mL-1. La regresión lineal para la curva de calibración es A = 0.78 + 0.005 C con un coeficiente de regresión (r) de 0.9982 (n = 11). El coeficiente de absorbitividad molar calculado fue de 2.213 × 10³ l mol-1 cm-1 y la sensibilidad de Sandell de 0.1954 µg cm-2. Los límites de detección y cuantificación calculados de acuerdo con la guía ICH son 0.73 y 2.21 µg mL-1, respectivamente. La precisión y exactitud de los ensayos fueron determinadas calculando la variación intra-día e inter-día a tres niveles de PPS; la desviación estándar relativa intra-día e inter-día fue < 3.09 % y la exactitud fue mejor que 3.5 %. Los métodos fueron exitosamente aplicados para la determinación de PPS en tres diferentes marcas de tabletas con buena exactitud y precisión y sin interferencia detectable por los excipientes. La exactitud fue asegurada realizando el análisis de un placebo blanco y una muestra sintética y también por los experimentos de recuperación vía el procedimiento de adiciones estándar.