Sugar and cyclitol determination in vegetables by HPLC using postcolumn fluorescent derivatization

Nonreducing sugars such as sucrose, raffinose, myo-inositol, pinitol and galactinol were separated on a polyamine-bonded polymer gel (NH 2 type) column using acetonitrile-water as mobile phase. Sugars in the eluate were detected by periodate oxidation and the subsequent derivation of guanidine to fluorescent compounds. Detection limits were: sucrose 2.5, D-glucose 2.5 and pinitol 4 ng. This highly sensitive method was more accurate and rapid for determining sugar contents in immature soybean seeds, sweet corn kernels and chinese mustard leaves than the conventional method using refractive index detection. Also, this method reduced the injection volumes of extracts to the column and allowed to lengthen the column life.