INVESTIGATION ON THE RESPONSE FACTORS OF CONCENTRATION DETECTORS WITHIN SEC PROCESS

The response factors of refractive index（RI） and ultraviolet（UV） detectors of size exclusion chromatography （SEC） defined as the ratio of area of output signal to the mass of injected sample are studied and analyzed by using five narrowly distributed polystyrene（PS） standard samples with known molar masses.It is found that the individual response factor for a given sample varies with the concentration of the injected solution within a limited range bounded by an upper and a lower limiting response factor values.This variation reveals the conformational change of the polymer chains with the concentration of the injected solution.The dynamic contact concentrations c_s of the PS samples derived from the response factor data are in good accordance with those reported earlier by other methods.The physical meanings of the signals of the two detectors are further analyzed and theoretically formulated.The solvation of the polymer chain and the conformation changes play an important role in these detecting systems.Both of the solvation number of the structural repeating unit and the extra embedded solvent due to cluster forming in higher concentrations could be deduced from the variation of response factor with the concentration of the injected solution.