DETERMINATION OF THE BAND BROADENING FUNCTION IN SIZE EXCLUSION CHROMATOGRAPHY WITH LIGHT-SCATTERING DETECTION

Abstract

This work describes the determination of the band broadening function (BBF) in a size exclusion chromatograph fitted with 2 mixed-gel columns, a light scattering (LS) detector, and a differential refractometer (DR). The raw data were the chromatograms of 4 narrow polystyrene standards. First, the interdetector volume shift was indirectly estimated from its upper and lower limiting values. Then, for each of the standards, their “local” BBFs were estimated by application of an existing theoretical method. Each local BBF is an assumed elution-volume invariant in the narrow ranges of the analyzed standards and is represented by an exponentially-modified Gaussian of standard deviation σ_BB and exponential decay τ_BB. Finally, a “global” BBF (valid for the complete fractionation range) was interpolated from the local BBF parameters. For increasing elution volumes, the global BBF exhibits an increasing σ_BB and a decreasing τ_BB. In addition, the asymmetry factor [τ_BB/σ_BB] and the global variance [] both decrease with elution volume.

Keywords:

• band broadening
• differential refractometer
• HPLC
• interdetector volume
• light scattering detector
• SEC

ACKNOWLEDGMENTS

This work was supported by the IUPAC project “Data Treatment in SEC and Other Techniques of Polymer Characterization. Correction for Band Broadening and Other Sources of Error” (http://www.iupac.org/web/ins/2009-019-2-400); by an international cooperation project between CONICET and the Slovak Academy of Sciences (SAS), and by the following Argentine institutions: ANPCyT (MinCyT), Universidad Nacional del Litoral, and Universidad Tecnológica Nacional.

Notes

The averages of rows (a) were calculated from s _DR(V) and logM(V) of Figure 1. The averages of rows (b) were calculated from s _DR(V+δ) and logM _w(V) as obtained through Eq. (1) with δ = 0.0733 mL.

*Estimated from . **Characterized by MALDI-ToF.