Validation of alternating least-squares multivariate curve resolution for chromatographic resolution and quantitation

The application of multivariate curve resolution using the alternating least-squares (ALS) method for the resolution and quantitation of mixtures of two co-eluted compounds is validated for hydrocortisone (main compound) and prednisone(impurity) in liquid chromatography with diode array detection. The recovery of the spectra of the co-eluted compounds and their quantitation are discussed in relation to the initial estimates provided by evolving factor analysis and SIMPLISMA methods. Quantitation errors below 1.5% have been obtained for the main compound for resolution values of 0.4 or above, and impurity concentrations in the range 0.5-20%.