HILIC-UV determination of lysine and chloride counterions in active pharmaceutical ingredients

A rapid, robust, and routinely applicable HILIC based HPLC-UV assay was developed for the quantitative determination of the L-Lysine content of Atorvastatin lysine active substance. During the method validation it turned out that with UV detection at 200 nm, the method is also capable for the direct determination of chloride ions. To the best of our knowledge, the phenomenon of chloride determination by short wavelength UV detection had only been once highlighted earlier in the literature. A wide range of the potential applications are demonstrated as well as the validation of the method as a routinely usable assay for residual chloride determination is also given.