Determination of the degree of esterification of alkaline de-esterified pectins by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) was used to determine the correlation between the migration times and alkaline-de-esterified pectins (ADPs) with various degrees (0%, 21%, 47%, 56%, 77% and 93%) of esterification (DEs) using 50 mM phosphate buffer (pH 6.5) as carrier electrolyte. It was observed that pectins with higher DE exhibited shorter migration time, regardless of the capillary length used. Good linearity was obtained with a correlation coefficient (r) as high as 0.994 and 0.998 when a capillary tubing with an effective length of 30 and 60 cm was used, respectively. In addition, separation of pectins was completed in 8 min using a tubing with an effective length of 30 cm. Correlation efficient was also found to be 0.995 when pectin mixture was separated by CZE, suggesting the efficiency and possible utilization of CZE for determination of pectin DE.