Band Broadening Correction Methods in GPC - SEC

MEIRA, G. R.; VEGA, J. R.

Dekker Encyclopedia of Chromatography, Second Edition - 2 Volume Set

Marcel Dekker Ed.

Año: 2005; p. 149 - 159

This Chapter reviews the main methods used to correct for band broadening (BB) in size exclusion chromatography (SEC). BB correction in SEC is still a non-totally solved issue, even when the molar mass distribution (MMD) of a linear homopolymer is determined with a mass detector and a molar mass calibration. Fortunately, modern SEC columns are highly efficient, and the correction for BB is mainly limited to the case of narrow-distributed polymers. Even in the presence of BB, if an instantaneous quality variable is accurately measured, then its corresponding global average will also be accurate. Numerical inversion techniques aim at correcting the raw chromatograms prior to determining the MMD or any other polymer quality characteristics. Their main advantage is that they admit arbitrary shapes for the chromatograms or the BB function. Their disadvantage however, is the ill-posedness of numerical inversions, that amplify the measurement noise. With molar mass sensitive detectors, two independent inversions are required prior to calculating the molar masses. In general, the BB function seems to be moderately uniform in the linear calibration range, but definitely skewed toward the higher retention volumes. Its determination is only simple for the low molar masses. In general, the BB function would be simpler to specify if the manufacturers of narrow standards provided the true MMDs of their samples.