ODD EVEN ALTERNATION IN THE AGGREGATION NUMBER DEPENDENCE OF STEPWISE AGGREGATION CONSTANTS

The micellar aggregation of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) is investigated by frontal gel filtration chromatography (GFC) at 25-degrees-C. From the concentration dependence of the centroid volumes of elution, the average aggregation numbers, n(w) and n(n), are determined as a function of total CHAPS concentration and the stepwise aggregation constants are determined as a function of the aggregation number. The odd-even alteration is found in the aggregation number dependence of the stepwise aggregation constants. The observed derivative GFC patterns are close to simulations based on these aggregation constants. Furthermore, the micelle size distribution is calculated from these aggregation constants.