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

An optimization study of sensitivity was performed in the determinatio n of azide by reversed-phase ion-interaction HPLC. Sensitivity was opt imized as a function of ion-interaction reagent concentration, ion-int eraction reagent chain length, and mobile phase flow rate. Different s eries of experiments were performed in which each new series was plann ed on the basis of the results of the previous one. The model included square and cubic terms and second-order interactions. An ordinary lea st-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 abou t the mean sensitivity. Chromatography under the improved experimental conditions predicted by the model gave a detection limit for sodium a zide of 6.0 ppb.