SIZE-EXCLUSION CALIBRATION CURVES FROM LIGHT-SCATTERING DETECTION - APPLICATION TO POLY(ETHYLENE-TEREPHTHALATE)

A simple method is proposed for using a size-exclusion chromatograph e quipped with both concentration and light-scattering detectors to cali brate other chromatographs having only concentration detectors. The me thod is developed and demonstrated for poly(ethylene terephthalate) in methylene chloride/dichloroacetic acid. It is shown that, in addition to circumventing the need for a light-scattering instrument on other chromatographs to be used for the analysis of PET, precision and accur acy of results are improved over those obtainable with light-scatterin g detection. The method uses averaging of the light-scattering detecto r data to establish a correlation between the molecular weight of the polymer of interest and the molecular weight of polystyrene at each re tention volume. This correlation can then be used for other instrument s employing the same mobile phase and only a concentration detector. A lthough the method assumes the validity of the universal calibration c urve, the actual curve is not required, nor are Mark-Houwink constants or intrinsic viscosities. (C) 1994 John Wiley and Sons, Inc.