A new method of extraction of amoxicillin using mixed reverse micelles

A completely new method of extraction of amoxicillin using solubilisation by mixed reverse micelles was proposed and the optimal conditions for the process were found. Mixed AOT-TWEEN 85 reverse micelles were used for the first time as a new approach for extraction of amoxicillin. The effects of different process variables such as AOT-TWEEN 85 molar fractions, total surfactant concentration, pH of aqueous feed solution and potassium chloride concentration during forward extraction; stripping aqueous phase pH, potassium chloride (KCl) concentration and extraction time during backward extraction were investigated and the optimal conditions were found for all mentioned parameters. With the aid of response surface methodology, the optimum conditions for forward extraction are identified as (i) 5.5:1 molar ratio of AOT/TWEEN 85, (ii) total surfactant concentration 102.57. g/L, (ii) pH 1.90, and (vi) KCl concentration 8.54. g/L. The percentage of amoxicillin solubilised in isooctane was 95.54% under these optimal conditions. On the other hand, the optimum conditions for backward extraction are identified as (i) stripping aqueous phase pH 6.58, (ii) KCl concentration 11.02. g/L, and (iii) extraction time 15. min. Under these optimal conditions, the percentage of amoxicillin recovered was 90.79%. AOT/TWEEN 85 mixed surfactant system shows a significant advantage of saving the amount of surfactant for forward extraction. The addition of non-ionic surfactant helps to preserve natural function/activity of antibiotics as compared with a pure AOT surfactant used. The optimum conditions were also found for a backward recovery of amoxicillin.