DIFFUSION-COEFFICIENTS IN LIQUIDS BY HPLC AND THE RESPECTIVE CALIBRATION FACTORS

When an analyte can be chromatographed on a HPLC column using a suitab le solvent, the diffusion coefficient of this analyte into the solvent can easily and accurately be determined, together with the calibratio n factor of the detector for this analyte. The experimental arrangemen t needed is based on a slight modification of the HPLC valve so that t he analyte is introduced into the chromatographic column via a short d iffusion column filled with the solvent. The new method is theoretical ly developed and the required mathematical relations have been derived . As an example, the diffusion coefficient of liquid benzene in chloro form, together with its calibration factor, are measured, under variou s experimental conditions, and the values found compare very well with that calculated by Wilke-Chang formula. Diffusivities and calibration factors of ions in aqueous liquid systems can also be determined by t he new method.