Pulp & Paper Products
Some interesting analytical challenges are posed by biopolymers from wood pulp and similar natural sources.
Lignins
Lignins tend to absorb laser light and fluoresce. Both phenomena lead to erroneous measurements of molar mass and size, unless the instrumentation and software can overcome these sources of error. The DAWN offers an optional infrared laser plus narrow bandpass optical filters on the detectors to minimize both total fluorescence and the amount reaching the detectors. In addition, the 'Forward Monitor' detector in the DAWN measures laser absorption by the sample to allow the ASTRA software to correct the measured molar mass.
Cellulose
Cellulose forms large, rod-shaped nanocrystals. While they may not be accommodated by standard GPC, these are readily separated by the Eclipse field-flow fractionation system, then measured downstream with a DAWN and possibly the WyattQELS integrated dynamic light scattering module. The shape of the nanocrystals is assessed from the dependence of molar mass on size, then fed back into the analysis to refine the accuracy of mass and size distributions.
Ligninler