CAPILLARY ELECTROPHORESIS OF HUMIC-ACID FRACTIONS

Capillary electrophoresis (CE) was used for the characterization of pe at humic acid (HA) fractions of different molecular weight. The HA wer e precipitated from a 0.1M NaOH plus 0.1M Na4P2O7 peat extract acidifi ed at pH < 2 with HCl. The HA fractions with different molecular weigh ts were obtained using an ultrafiltration system. Using phosphate (pH 9) as running buffer, the peaks of the CE profiles were not well resol ved, but using berate (pH 8.5) as the running buffer, the resolution o f the peaks was improved. The highest resolution of the profiles was o btained using berate as the running buffer with the HA fractions of lo wer molecular weights. Using both phosphate and berate as the running buffer, the elution time for the HA fractions appeared at shorter time s as the molecular size of the HA fractions decreased.