VISCOSITY MOLECULAR-WEIGHT DETERMINATION OF POLYADENYLIC-ACID

In this study viscosity measurements of polyadenylic acid (PolyA) in a queous solution were carried out under different conditions. In the ab sence of any additives, the polymer degraded during flow through the c apillary of a viscometer or when standing still. Degradation during th e former was more severe. The degradation of polyadenylic acid can be prevented by addition of an electrolyte such as KCI to increase the io nic strength. However, in this case the deviation from linearity was s till considerable at most ionic strength values. The best fit to the H uggins and Kraemer ecuations was obtained using a Tris-EDTA buffer sol ution with a final pH of 7.65. Estimation from intrinsic viscosity and weight-average molecular weight values gave kappa and alpha as 2.04 x 10(-5) and 0.89 from the equation eta = kappa M(alpha). The differenc e between Huggins (k(1)) and Kraemer (k(1)') constants was close to 0. 50 for all measurements.