Non-ionic micellar affinity capillary electrophoresis for analysis of interactions between micelles and drugs

Micellar affinity capillary electrophoresis (MACE) was introduced to evalua te the affinity of various kinds of drugs as benzoic acid, salicylic acid, trinitrophenol, p-hydroxybenzoic acid and o-acetylsalicylic acid. Non-ionic micelles as Brij 35 (polyethylenglycol dodecylether), Tagat (polyoxyethyle ne (20) glycerol monooleate) and Tween 20 (polyoxyethylen sorbitan monolaur ate) were used as a pseudostationary phase in capillary electrophoresis. Fo r polyvinyl alcohol (PVA) coated capillary was used in this examinations. T he drugs had negative electrophoretic mobilities at a pH value of pH 7.2. T he negatively charged drugs migrated toward the anode and were related by t heir interaction with the micelles. The difference in the mobility of the d rugs owing to the presence of the micelles reflected the interaction betwee n these drugs acid the micelles. Equations were derived to calculate the ca pacity factor k' from the migration times in the presence of micelles t' an d in the absence of micelles t, the partition coefficients P-wm and thr Gib bs free energy. The drugs show different interaction and affinity with the micelles in the systems. Strong interaction was observed between benzoic ac id and the micelles. Furthermore, a linear relationship (R = 0.999) was obt ained between DeltaG degrees and in P-wm in the micellar. solubilization of drugs. These results show that DeltaG degrees call give us information on the affinity and on the partition behaviour of the drugs in these systems. (C) 2001 Elsevier Science B.V. All rights reserved.