Investigations on Synthesized Azo Compound, [4-((4-Hydroxynaphthalen-1-yl) Diazenyl) Benzoic Acid] (p-ABAαN), as an Acid-Base Indicator
William Kofie *
Drug Analysis Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
Cedric Dzidzor Amengor
Drug Analysis Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
Emmanuel Orman
Drug Analysis Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
*Author to whom correspondence should be addressed.
Abstract
Aim: To evaluate the indicator properties of a synthesized azo compound to be used as a suitable substitute for standard indicators
Methodology: Compound, [4-((4-hydroxynaphthalen-1yl)diazenyl) benzoic acid](p-ABAαN) was synthesized using standard diazotization and coupling procedures. Initial evidence indicated that [4-((4-hydroxynaphthalen-1-yl) diazenyl benzoic acid] (p-ABAαN) exhibited sharp colour changes in acidic, neutral and alkaline pH media. Indicator properties in acid-base neutralization reactions were evaluated, and the results compared with that of phenolphthalein and methyl orange. The indicator, p-ABAαN was also used to assay Ibuprofen and validated upon comparison with official monograph (British Pharmacopoeia (2010) method). Results obtained were statistically analysed using t-test and One-Way Analysis Of Variance (One Way ANOVA) at 95% confidence level from Graph Pad Prism (version 6, 2012).
Results: The use of p-ABAαN in acid - base neutralization reactions involving strong acid / strong base and weak acid / strong base were experimentally verified and validated. Validation was also carried out for the use of p-ABAαN in titrimetric assay of Ibuprofen.
Conclusion: p-ABAαN [4-((4-hydroxynaphthalen-1-yl) diazenyl) benzoic acid] proved to be a suitable indicator for the titrimetric assay of Ibuprofen and in various acid-base titration experiments.
Keywords: Azo dye, indicator, methyl orange, phenolphthalein, titrimetry, validation