This application note introduces the GPC analysis method for poly(n-isopropylacrylamide) (PNIPAM) smart materials using the Agilent 390-MDS multi-detector suite and universal calibration method.
The document explains how 'smart materials' like Poly(n-isopropylacrylamide) (PNIPAM) hydrogels change physical properties in response to stimuli such as temperature. Accurate measurement of their molecular weight distribution is critical for controlling drug release and uptake properties.
Standard GPC using only concentration detectors provides results relative to calibration standards, which may not be chemically identical to the sample. This note details a method using the Agilent 390-MDS Multi Detector Suite with online viscometry and differential refractive index (DRI) detection. By employing universal calibration based on molecular size in solution rather than just chemical identity, this technique provides accurate absolute molecular weights even when standards differ from the sample polymer.
| Columns | 2x Agilent PLgel 5 pm MIXED-C, 300 x 7.5 mm |
|---|---|
| Eluent | THF + 5% triethylamine |
| Flow Rate | 1.0 mL/min |
| Detector Train | 390-MDS incorporating Viscometer and DRI |
| Detector Temp | All detectors set at 40 °C |
Universal calibration allows accurate calculation of molecular weights even when polymer standards are not chemically identical to the sample, as it separates based on size rather than molecular weight.
The setup uses a viscometer and a differential refractive index (DRI) detector within the 390-MDS.
Conventional GPC with a concentration detector gives only relative results based on standards, whereas viscometry employing the 390-MDS provides an accurate representation of molecular weights regardless of calibrants used.