Instrumentation for Molecular Weight Determination

While chemical instrumentation models tend to change rapidly with time, the basic operation and typical results of many instmments tends to change somewhat slower. Table 3.14 lists some current models for molecular weight determination. In this case, the instmmentation emphasized by Brice-Phoenix provides an absolute weight-average molecular weight of polymers via Zimm plot analysis. 

Polymer Laboratories GPC and HPLC instmmentation by themselves provide relative molecular weights and molecular weight distributions, requiring calibration. However, once set up, molecular weights can be determined on a variety of polymers, at a rate of two determinations an hour or better. The addition of light-scattering provides absolute molecular weights. 

The Physical Electronics TRIFT II MS provides absolute molecular weights at the low end of the polymer molecular weight range. It can also help determine end groups and other moieties. 

Light-scattering Photometer OM-2000 Brice-Phoenix Absolute values via Zimm plots 

PL-GPC-120 ,with differential refractive index and multiple angle hght-scattering, and temperature controlled oven and dual detectors Polymer Laboratories Molecular weights and molecular weight distributions 

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