3.2.1. Selectivity The ability of the method to detect e-caprolactam, melamine and urea being free from any interference is defined as selectivity. The procedure allowed determination of these compounds inde- pendent of other components present in any povidone sample. The selectivity of the method was confirmed by comparing the electropherograms obtained from the MEKC analysis of a blank sample (Fig. 2A), a pure povidone sample at 20 mg/ml (Fig. 2B).