Define Free Solution or Moving Boundary Method?
The first electrophoresis technique used in the study of protein was free solution or moving boundary method devised by Tselius in 1937. A buffered protein solution occupied the lower part of a quartz U-tube forming a sharp boundary with protein free buffer solution which lay above it in both limbs of the U-tube and with which electrodes were in contact. On application of an electrical potential difference, proteins migrated to the appropriate electrode at varying speeds and the sharp boundary was disturbed. The position of the boundary for each protein could be determined by observing the change in refractive index which occurs at this point.
Separation occurs only at the boundaries, the bulk of the protein remaining homogenous. Using this technique human proteins can be resolved into albumin and three globulin zones α (alpha), β (beta)and γ (gama), in order of decreasing mobility. This is moving boundary or frontal electrophoresis. The technique is still used in research for the measurement of electrophoretic mobility and for the study of protein-protein interaction but is not used in clinical laboratories for routine work since a complex apparatus is needed, the technique is difficult and samples of the order of 0.5 ml of serum are required.