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New Derivatization Methodology of 4-aminobenzoic Acid from its Dietary Supplements: Kinetic Spectrophotometric Methods for Determination

[ Vol. 15 , Issue. 7 ]


Naser A. Naser*, Kasim M. Alasedi and Zainab A. Khan   Pages 752 - 768 ( 17 )


Background: A new approach describing the validation and development of an easy, new spectrophotometric and kinetic method for identification of para-aminobenzoic acid in dietary supplement has been performed. In this study, para-aminobenzoic acid was derived in a pH-controlled environment, as a new organic compound 4(4-Benzophenylazo)pyrogallol, by incorporating diazotized para-aminobenzoic acid with pyrogallol.

Objective: The determination of para-aminobenzoic acid was conducted by the fixed time and initial rate techniques. These approaches were based on the reaction of the compound containing paraaminobenzoic acid, 4(4-Benzophenylazo)pyrogallol, with Ag(I) to form colored product with a maximum absorbance at 468nm. Both of these techniques were adopted for constructing the calibration curves and examined for their suitability for the quantitation of para-aminobenzoic acid in dietary supplement.

Methods: The determination process was established, using initial rate and fixed time kinetic spectrophotometric methods.

Results: 4(4-Benzophenylazo)pyrogallol was characterized using proton-nuclear magnetic resonance, Fourier-transform infrared, differential scanning calorimetry and thermogravimetric thermal methods, gas chromatography–mass techniques, and solvatochromic behavior in solvents with different polarities was also examined.

Conclusion: For the first time, para-aminobenzoic acid was well determined by incorporating it as an organic solid compound, 4(4-Benzophenylazo)pyrogallol, through coupling pyrogallol with diazotized para-aminobenzoic acid in regulated pH medium, ranging between 5.0 to 6.0. The existence of common excipients in the dietary supplement did not produce any significant interference. F- and ttest data analysis were used for statistical comparison of the suggested techniques with that of reference method, demonstrating excellent agreement with no significant difference in the associated precision and accuracy.


4-aminobenzoic, derivatization, determination, dietary supplement, kinetic methods of analysis, solvatochromic.


Department of Chemistry, Faculty of Science, University of Kufa, P.O. Box (21), Najaf Governorate, ALSheik Al-tousi University College, An-najaf al-ashraf, P.O. Box (9), Department of Chemistry, Faculty of Education for Girls, University of Kufa, P.O. Box (21), Najaf Governorate

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