THEORETICAL-STUDY OF THE ACCURACY AND PRECISION OF THE MEASUREMENT OF SINGLE-COMPONENT ISOTHERMS BY THE ELUTION BY CHARACTERISTIC POINT METHOD

Using the epuilibrium-dispersive model of chromatography, band profiles corresponding to a known Langmuir isotherm are calculated. A noise sequence is added to the calculated profile to simulate an actual chromatogram. The elution by characteristic point (ECP) method of isotherm calculation is then applied to this profile, and the derived isotherm is compared with the initial one. Significant differences between the ''true'' and the ''measured'' isotherms are observed at low or moderate column efficiencies. The direct method of determination of the isotherm from the band profile based on the numerical solution of the inverse mathematical problem gives more accurate results than ECP, especially at low column efficiency. It is recommended to use the ECP method only when the column efficiency exceeds markedly 2000 theoretical plates.