SYSTEMATIC DEVIATIONS DUE TO RANDOM NOISE-LEVELS IN SIZE-EXCLUSION CHROMATOGRAPHY COUPLED WITH MULTI ANGLE LASER-LIGHT SCATTERING

Starting from a theoretical molar mass distribution (generalized expon ential distribution), the concentration and light scattering chromatog rams of a size exlusion chromatography coupled with multi angle laser light scattering experiment are constructed with random noise levels. From these noisy curves, a log M versus retention volume plot is creat ed. This plot shows a systematic deviation in the low and high molar m ass region. In the low molar mass region (poor light scattering signal s), the log M signals are systematically too high. In the high molar m ass region (poor concentration signals), the log M signals are constan tly too low. We show that this systematic error is due to the fact tha t the logarithm of negative numbers is not defined.