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6.4. SIZE-‐EXCLUSION CHROMATOGRAPHY COMBINED
WITH ON-‐LINE
LIGHT SCATTERING
(SEC-‐MALLS)
6.4.1. General
SEC-MALLS is probably the most common method to determine molecular
weight distributions (and averages). All components are commercially
available for measurements, and software is available for all data processing.
SEC-MALLS is based on the use of two on-line detectors in the
chromatographic set-up:
•
A concentration sensitive detector (refractive index or UV detector)
•
A light scattering detector, which monitors scattering at up to 18 angles
simultaneously.
The figure below shows an example.
The software records raw data from the detectors at regular intervals. A single
experiment is divided into 1000-5000 ‘elution slices’ (typically 0.1 ml) which