SEDIMENTATION FIELD-FLOW FRACTIONATION - A NEW TECHNIQUE FOR THE FRACTIONATION OF SOIL COLLOIDS

Sedimentation field-flow fractionation has produced high resolution separations for a range of macromolecules and particles. The application of the technique for separation of soil colloids of submicron size is the subject of a preliminary study reported here. Fractions of relatively narrow particle size were obtained in the size range up to 0.50-mu-m. The fractions were generated in a much shorter time than standard methods of fractionation such as centrifugation in a continuous action rotor. Analysis by electron microscopy combined with inductively coupled plasma mass spectrometry are the most promising techniques that can be applied to define the chemistry and mineralogy of the fractions. The main disadvantage for clay mineral studies is that the small mass of each size fraction obtained limits the utility of X-ray diffraction.