Abstract: Pharmaceutical filed requires high quality standards. Various kinds of process are carried out to maintain high quality standards. Analytical science plays an important role to control as well as to assure the standard of pharmaceutical products. Varity of analytical and separating techniques are currently in used for the qualitative and quantitative analysis of products. Field Flow Fractionation (FFF) is one of the most versatile separating techniques among all other techniques. Various kinds of FFF techniques are under used. Aim of this review is to provide information about various FFF techniques and give brief application of FFF in biotechnological field.
Day by day newer and newer products come in the market from pharmaceutical and biotechnological field. High quality standard is the requirement of today's market. There are numbers of separating techniques and analytical techniques for the qualitative and quantitative analysis of various products like chromatographically techniques. Field Flow Fractionation (FFF) is an emerging separation technique, which has been proven successful in the analysis of pharmaceuticals, biotechnology products, polymers, soils, and foods, among others.
Principle of FFF
The mechanism of separation in normal (polarization) Field-Flow Fractionation (FFF) is based on the interaction of the retained species with the physical field acting across a thin channel, perpendicularly to the flow of a carrier liquid. Carrier liquid flowing along the channel forms a nearly parabolic flow velocity profile across the channel. Each retained species forms a nearly exponential concentration profile across the channel due to the field generated flux and the opposed diffusion flux. Larger species exhibiting lower diffusion coefficients are usually compressed closer to the accumulation wall in a zone of lower longitudinal velocity of the carrier liquid. The elution order is thus from the small to the large size species in this polarization mechanism. On the other hand, if the distances of the center of gravity of the concentration profiles of the retained species from the accumulation wall are commensurable with their size, the elution order is inverted and the steric exclusion mechanism can govern the separation because the retained species cannot approach the accumulation wall closer than their radius and thus larger species elute with higher average longitudinal velocity. Such a situation appears if the field strength is high enough so that all species are compressed to the accumulation wall independently of their size.