The importance of an accurate value for the interdetector volume between a low-angle laser light scattering (LALLS) photometer and a concentration-sensitive detector on the calculation of local weight average molecular weights from size exclusion chromatography is discussed. Several methods of measuring interdetector volumes using narrow polymer standards are compared. Best results are obtained when peak onsets are used rather than peak maxima. An alternative approach that uses the LALLS as an absorption spectrophotometer is presented.
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