Striegel AM (2017) In: Fanali S, Haddad PR, Poole CF, Schoenmakers PJ, Lloyd D (eds) Liquid chromatography: fundamentals and instrumentation, 2nd edn. Results of these determinations are presented here, along with the relevant experimental data. In all cases, this has been done by off-line, batch-mode differential refractometry, not by assuming 100% analyte column recovery and 100% accurate peak integration. For the last 17 years, the author’s laboratories have measured the ∂ n/∂ c of a variety of natural and synthetic polymers, at both 690 nm and, more recently, 660 nm, under a variety of solvent and temperature conditions. However, not only does ∂ n/∂ c differ among chemical species, it also depends on experimental conditions such as solvent, temperature, and wavelength. The ∂ n/∂ c is also needed for accurate determination of the weight-average molar mass of polymers by off-line, batch-mode multi-angle static light scattering.
The latter include methods such as size-exclusion and hydrodynamic chromatography, and asymmetric and hollow-fiber flow field-flow fractionation. The specific refractive index increment (∂ n/∂ c) is an essential datum for the accurate quantitation of molar mass averages and distributions (inter alia) of macromolecules when refractometry, static light scattering, and/or viscometry detection are coupled on-line to size-based separation techniques.
