High and low molecular weight fractions of humic and fulvic acids

✍ Scribed by K. H. Tan

• Publisher: Springer
• Year: 1977
• Tongue: English
• Weight: 499 KB
• Volume: 48
• Category: Article
• ISSN: 0032-079X
• DOI: 10.1007/bf00015160

✦ Synopsis

The present investigation was initiated to study molecular weight fractionation of humic compounds isolated from surface samples of an Ultisol (Red Yellow Podzolic soil) and a Spodosol (Podzol), using fine (mol. wt. cutoff 3500) and coarse (mol. wt. cutoff 12000) dialysis membranes and sephadex gel filtration. Characterization of the humic fractions was conducted by elemental analysis and infrared spectroscopy. The results confirmed t h a t fulvic acid (FA) was higher in ash and elemental content t h a n humie acid (HA). W i t h careful purification the a m o u n t of ash was found to be reduced to a minimum, but not to zero. Sephadex gel filtration revealed that fine H A (obtained with fine membranes) was composed of smaller amounts of H A -I (high mol. wt.) and large amounts of H A -I I (low mol. wt. fraction). Coarse H A (obtained with coarse membranes) had almost equal amounts of H A -I and H A -I I . Fine or coarse F A yielded only low molecular weight components after elution through sephadex. Infrared spectra of the humic fractions were indicative for the presence of phosphoglyceric acid as a possible constituent of the low molecular weight fraction of humic compounds.