Intrinsic Viscosity Methods in Natural Polymer as Pharmaceutical Excipients

Intrinsic viscosity is the most economical and used measure in the determination of polymers and biopolymers used as excipients in the pharmaceutical industry. The most used methods in the measurement of intrinsic viscosity are Huggins, Kraemer, Schulze-Blashke and Martin, the first being used as a standard and reference for the others. There are also Simple Point methods such as Solomon Ciuta and others that help in this regard. In this chapter, we will focus on those methods best known and applied in intrinsic viscosity measurements. In the measurement of intrinsic viscosity in dilute solutions of polymers, experimental methods such as Huggins, Martin, Kraemer and Shulze-Blashke are particularly useful. In dilute concentrations, graphical methods such as those of Fuoss, Fidors, and Tanglertpaibul and Rao can also be used without major errors. Although there are many more methods these can be more difficult and impractical in their calculations and graphs. The methods furthest from experimental practicality are those that depend on other methods and constants, such as Budtov's and Baker´s. As for the simple point methods, the simplest and most used is that of Solomon-Ciuta, the rest have similar or better results. As for the proposed methods, the most prominent and with the least error is Square, the rest being affordable but with a somewhat higher margin of error