Interference of chitosan in glucose analysis by high-performance liquid chromatography with evaporative light scattering detection

The purpose of this work was to quantify glucose in aqueous solutions containing chitosan by high-performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD). Chitosan is a natural compound that is used alone or as an additive in several formulations. Microencapsulation of bioactive compounds such as glucose, by means of chitosan, is being explored, but difficulties arise when glucose needs to be determined in the presence of chitosan. HPLC is the technique most commonly used for glucose analysis, and ELSD may offer advantages (e.g. sensitivty and the possibility of operating in gradient mode) compared with other detectors. The influence of chitosan in the analysis of glucose by HPLC with ELSD was investigated at different pH values of the aqueous solutions. Isocratic elution with an acetonitrile/water mixture (80:20, v/v) and water washing between runs were the best options to avoid the mucoadhesive properties of chitosan, which are responsible for column degradation and variability of the retention time of glucose. The developed methodology was considered completely adequate for rapid glucose analysis in aqueous solutions with low pH (< 3), in the presence of chitosan.