Derivation of hydroxamic acid from pectin and its applications in colorimetric determination.

A hydroxamic acid (HX) derivative of pectin was prepared, and its potential application to simple colorimetric determination of polysaccharides was investigated. The coupling reaction between pectin and hydroxylamine (HA) progresses in the presence of 1-cyclohexyl-3-(2-morpholinoethyl) carbodiimide metho-p-toluenesulfonate (CMEC). The calibration curve for pectin showed good agreement and the lower limit of detection was 0.5 mg. This is a very simple and rapid determination method, which does not require tedious pre-treatment, for polysaccharides containing carboxyl groups.