One of the most useful characterization methods in polymer science is widely acknowledged as SEC (Size-Exclusion-Chromatography) or GPC (Gel Permeation Chromatography).
Figure 1: Schematic of a generic refractive index detector, showing the key components
The method provides the ability to establish molecular weight distribution and its averages, to give a complete picture of the polymer sample being examined. After column separation, in standard GPC/SEC, a concentration detector is usually utilized to record a signal proportional to the relative concentration of the sample.
A Differential Refractive Index (DRI) detector is most frequently employed for this task, as the majority of synthetic polymers are not UV active.
GPC/SEC can be a time-consuming method, with a single measurement often taking up to 60 minutes with the resultant chromatogram having to be related to calibration curve data gathered in the days prior. The accurate calculation of molecular weight via GPC/SEC is therefore highly dependent on baseline stability because of this. These facts confirm just how crucial minimizing DRI detector signal drift is in a GPC/SEC system.
This article outlines how the design of a differential refractive index detector has been enhanced resulting in decreased baseline drift and improved overall GPC/SEC system performance, enhancing the accuracy of results...
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This information has been sourced, reviewed, and adapted from materials provided by Testa Analytical Solutions - OEM Division.
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