CORRECTION FOR INTERDETECTOR VOLUME IN SIZE-EXCLUSION CHROMATOGRAPHY (SEC)

In a multidetector SEC system it is necessary to match the outputs of the detectors that sense eluant concentration with those that are mole cular weight dependent. There are several methods to accomplish this. The most common is to determine the interdetector volume or time diffe rence between detectors. The difficulty with this technique is that wi th detector systems where the column eluent is split, the interdetecto r time difference Varies with solution viscosity. Two new techniques w ere implemented on a high temperature SEC/DRI/LALLS/VISC system which take into account changes in solution viscosity due to high molecular weight polymers. Both techniques use calibration curves of hydrodynami c volume versus elution volume for the different detectors to determin e the ''instantaneous'' time difference between the detectors as it va ries with solution viscosity. Either method provides the correct inter detector time lag information. We note also that in multidetector syst ems the configuration of the detectors should be such as to maximize s olvent flow rates through each detector and hence to minimize band bro adening effects. (C) 1995 John Wiley & Sons, Inc.