ABSTRACT
Indicators are used to determine the equivalence point in acid � base titrations (neutralization titrations). They exhibit sharp color change with respect to change in pH. Popularly used indicators for neutralization titrations are synthetic chemicals. They are found to have hazardous effects in human body. The highly colored pigments obtained from plants are found to exhibit color changes with variation in pH. A study was done to check the indicator action of aqueous extract of flower pigments and compared with that of already existing synthetic indicators. Extraction was done using hot water and a definite volume of extract was added which gave accurate and reliable results for different types of neutralization titrations - strong base against strong acid, strong acid against a weak base, weak base against strong acid and weak acid against weak base. The work proved to be acceptable in introducing flower pigments as a suitable substitute to the synthetic indicators.
ABSTRACT
Methyl salicylate is chemically methyl-O-hydroxybenzoate and act as an active ingredient in many topical analgesic preparations. It posses good counter irritant activity. In this present study, a colorimetric method is developed for the quantitative estimation of methyl salicylate, both in the bulk form and in the formulations. A dark bluish – purple colour is formed between methyl salicylate and ferric chloride reagent. The intensity of the colour is directly related to the concentration of methyl salicylate present. The developed method was simple and gave accurate and precise results. The developed colour had its maximum value of absorbance at 537 nm when scanned in the visible region. The absorbance of the coloured system was measured at 537 nm. Beer’s law was obeyed in the range of 12 to 72 μg/mL. The equation for the straight line was found to be, y = 0.0075 x + 0.002 with correlation coefficient value of 0.996. The developed method was applied to semi – solid formulations for the quantitative estimation of methyl salicylate. The percentage of recovery was between 99.62 % in the formulation. The method proved to be a convenient analytical tool for the quantity determination of methyl salicylate.
ABSTRACT
Indicators help to determine the equivalence point in acid – base titrations (neutralization titrations). They show sharp color change with respect to change in pH. Commonly used indicators for neutralization titrations are synthetic in nature. They are found to posses hazardous effects in human body. The highly colored pigments obtained from plants are found to exhibit color changes with variation of pH. A study has been done to investigate the indicator activity of aqueous extract of flower pigments and compared with that of already existing synthetic indicators. Pigments were extracted using hot water and a definite volume was added which gave accurate and reliable results for all the four different types of neutralization titrations - strong acid against strong base, strong acid against a weak base, weak acid against strong base and weak acid against weak base. The work proved to be acceptable in introduc-ing flower pigments as a substitute to the synthetic acid-base indicators.
ABSTRACT
Indicators help to determine the equivalence point in acid – base titrations (neutralization titrations). They show sharp color change with respect to change in pH. Commonly used indicators for neutralization titrations are synthetic in nature. They are found to posses hazardous effects in human body. The highly colored pigments obtained from plants are found to exhibit color changes with variation of pH. A study has been done to investigate the indicator activity of aqueous extract of flower pigments and compared with that of already existing synthetic indicators. Pigments were extracted using hot water and a definite volume was added which gave accurate and reliable results for all the four different types of neutralization titrations - strong acid against strong base, strong acid against a weak base, weak acid against strong base and weak acid against weak base. The work proved to be acceptable in introduc-ing flower pigments as a substitute to the synthetic acid-base indicators.