On the use of response surface strategy to elucidate the electrophoretic migration of carbohydrates and optimize their separation

Abstract

This paper focuses on the optimization with a design of experiments of a new CE method for the simultaneous separation of four carbohydrates of interest (fructose, glucose, lactose, and sucrose) and five potentially interfering carbohydrates (ribose, xylose, maltose, mannose, and galactose) with a highly alkaline separation electrolyte for subsequent applications to food, beverage, forensic, or pharmaceutical samples. First, the factors that potentially affect the carbohydrate migration were identified: NaOH concentration in the separation electrolyte, separation temperature, and separation electrolyte conductivity. A central composite design was then carried out to determine and model the effects of these three factors on normalized migration times and separation efficiency. From the model, an optimization of the separation was carried out using a desirability analysis based on resolutions between adjacent peaks and analysis time. The optimum conditions obtained were a separation electrolyte composed of 98 mM NaOH and 120 mM NaCl to adjust the conductivity at 4.29 S/m and a separation temperature fixed at 26.5°C. Finally, these conditions were experimentally confirmed and the robustness of the obtained separation was checked.