Effects of different high pH solutions on the chemical stability of immobilized-polymer stationary phases

Abstract

Many chromatographic separations require high pH mobile phases for the elution of basic compounds with symmetrical peaks appropriate for quantitation. Phosphate and carbonate salts are the most common additives used to achieve these conditions. However, they act in different ways on the stability of silica-based stationary phases. To provide a faster evaluation of the effects of these high pH solutions on the column lifetime of new immobilized-polymer metalized-silica-based phases prepared in our laboratory, an accelerated stability test at a nominal pH of 10 and at 50°C was developed and applied with monitoring of the retention factor, column efficiency, and asymmetry as functions of the volume of high pH mobile phase. The laboratory-made stationary phases presented chemical stabilities in phosphate solution more than three times better their chemical stabilities in carbonate buffer.