ASSESSMENT OF CHROMATOGRAPHIC PEAK PURITY BY MEANS OF MULTIWAVELENGTH DETECTION AND CORRELATION-BASED ALGORITHMS

Dual-wavelength UV detection is widely employed to generate absorbance ratios as a relatively non-specific method for characterizing peak purity in liquid chromatography. The sensitivity of this method is largely dependent on the pair of wavelengths chosen. An alternative technique, correlation of the spectral information, proposed primarily to overcome this constraint, has been investigated. The implications for the application of correlation coefficients to peak purity and homogeneity determination are examined. Particular attention is focused on the successful use of correlating multiple chromatographic peak-area data (peak areas calculated from the absorbance values at various detection wavelengths) for the reliable assessment of both peak identity and peak homogeneity. Using a model system, 1% of a putative related compound of sulphasalazine in a mixture with sulphasalazine could be detected regardless of the chromatographic resolution between the two compounds.