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Effect of pH on the encapsulation of the atrazine by - cyclodextrin at 25C

Jamil Rima, Karin Assaker, Layal Gemayel

The encapsulation of atrazine by -cyclodextrin has been studied through UV absorption enhancement measurements in aqueous solutions at 25C. This study has been carried out at pH= 0.7, 4, 5,9 and 11. Since the pKa of the atrazine system is 1.68 at 25ï‚°C, the protonated (HA) of atrazine should be present at pH less than 1.68. The association constants K of -CD/atrazine have been determined at different values of pH by using linear and nonlinear regression analysis of the experimental data.The Kvalues obtained were 311 ± 15; 254 ± 15 and 150 ± 15 at the pH 5; 7.3 and 9 respectively.