CHEMOMETRIC OPTIMIZATION OF AZIDE SENSITIVITY IN REVERSED-PHASE ION-INTERACTION HPLC

An optimization study of sensitivity was performed in the determination of azide by reversed-phase ion-interaction HPLC. Sensitivity was optimized as a function of ion-interaction reagent concentration, ion-interaction reagent chain length, and mobile phase flow rate. Different series of experiments were performed in which each new series was planned on the basis of the results of the previous one. The model included square and cubic terms and second-order interactions. An ordinary least-squares (OLS) method was used as the regression method, and the all-model search was applied. The Fisher F test and R(2) values were used to estimate the regression model quality. The model proposed contains five parameters and explains 98.21% of the variation in the data about the mean sensitivity. Chromatography under the improved experimental conditions predicted by the model gave a detection limit for sodium azide of 6.0 ppb.