Abstract

STUDIES ON SPECTRAL BEHAVIOUR OF PARA AMINO SALICYLIC ACID IN MICELLAR MEDIA

Seema Acharya and Rajneesh Hingonia*

ABSTRACT

The interaction of 4-Amino Salicylic Acid or Para Amino Salicylic Acid (PAS) a clinically and pharmacologically imaportant molecule with nonionic and ionic micelles of surfactants has been studied by absorption and fluorescence spectral technique. It has been found by both laboratory and clinical experiments that the compound has a better effectiveness against tubercle bacilli. Nonionic surfactants, TX- 100 & Tween-80 initially increased the fluorescence intensity at their lower concentrations and then decreased it on increasing their concentration with bathochromic shift of 5nm in emission peak. Tween-20 gradually increased the emission peak height without any shift. The ionic surfactants both anionics and cationics enhanced the fluorescence intensity except CPC which quenched it. Among the anionics DBSS exerted the intensity to the maximum with hypsochromic shift of 30nm. Fluorescence intensity enhanced on increasing the concentration of the solvent (methanol) accompanied by a hypsochromic shift of 10nm. The dual nature of surfactant micelles is responsible for the occurrence of properties of surface activity, micellization followed by solubilization. This has also been confirmed by few theoretically calculated spectral parameters like, empirical fluorescence coefficient ( f k ), quantum yield ( f  ), molar extinction coefficient (ε) and Stokes’ shift. The calculated results are in good agreement with the experimental observations.

Keywords: Fluorescence, PAS, Micelles, Solubilization.