Estimation of molecular weights of peptides by determination of height equivalent to a theoretical plate in size-exclusion chromatography

The analysis of the flow-rate required to obtain the optimum height equivalent to a theoretical plate, HETP, has been used to estimate the molecular weight, MW, of peptides in size-exclusion chromatography. A straight line is obtained when log MW is plotted against the flow-rate which gives the optimum HETP. This relationship holds even for peptides which adsorb to column packings. The typical quantity of peptide required is 1 nmol and analysis time was less than 2 h. The method is applied to peptides of 200–10,000, and the precision is ±20%. The method may be applicable to the analysis of MW for all classes of compounds.