Influence of secondary interactions on high performance size exclusion chromatography. Application to the fractionation of landfill leachates

The leachates from municipal landfills are characterised by the complex che mical distribution and wide molecular weights range of their constituents. We have designed a high performance size exclusion chromatography method to take into account these two aspects. By using eluents of low ionic strengt h, electrostatic interactions between the eluted molecules and the negative sites of the stationary phase are enhanced. Thus, the compounds are eluted mostly according to their physico-chemical properties. Contrarily, using e luents of high ionic strength allows eliminating most of these electrostati c interactions which, in turn, permits to estimate the molecular weights, s ince steric exclusion is then the dominating mechanism of separation. A spe ctroscopic fingerprint may also be determined through multidetection (UV ab sorption: fluorescence and evaporative light scattering detection) coupled on line which allows to sort out the compounds into a few number of familie s.