May 24 2021
The new HK Series Differential Refractometer from Testa Analytical Solutions eK sets a benchmark for precise determination of specific refractive index increment (dn/dc) - an important parameter for polymer and protein molecular weight determination using light scattering techniques.
The specific refractive index increment (dn/dc) is one of the most underestimated parameters in material science. The assumption that using the approximate values for many polymers and proteins in published literature will not have a huge impact on molecular weight values determined by light scattering experiments, with or without GPC/SEC separation is incorrect. Because dn/dc is a squared term in the Debye Constant of the Zimm equation, any error in determining dn/dc will result in introducing considerable errors into molecular weight determination. In addition to this, precise determination of dn/dc within a GPC/SEC application, is extremely useful in order to calculate mass-balance of the separation, and therefore determine presence of absorption on the column which can again negatively influence any results calculated.