Analysis of polyhexamethylene biguanide and alexidine in contact lens solutions using capillary electrophoresis, ultra-performance liquid chromatography and quadrupole time of flight mass spectrometry.

Polymeric biguanides, as well as quaternary ammonium compounds, are ubiquitous antimicrobial agents in healthcare. Due to the highly cationic and polymeric nature of these compounds and the complex matrices in which they are found, the analytical characterization of products containing them remains challenging. In this work an efficient, sensitive, and high-resolution separation protocol was developed to perform quantitative measurements (sub-mg L) of alexidine dihydrochloride (ADH) and polyhexamethylene biguanide (PHMB) in commercial multipurpose contact lens solutions (MPS).