Determination of polyhexamethylene biguanide hydrochloride using a lactone-rhodamine B-based fluorescence optode

A new determination method for polyhexamethylene biguanide hydrochloride (PHMB) using a lactone-rhodamine B (L-RB) based fluorescence optode has been developed. The optode membrane consists of 2-nitrophenyl octyl ether as a plasticizer, L-RB, and poly (vinyl chloride). The optode responds to tetrakis (4-fluorophenyl) borate, sodium salt (NaTPBF) in the µM range. The fluorescence intensity of the L-RB film for PHMB solution containing 20 µM NaTPBF decreased linearly as the concentration of the PHMB solution increased in the concentration range from 0 to 8.0 µM, which shows that PHMB with a concentration range of 0 to 8.0 µM is determined by the L-RB film optode. The concentration of PHMB in the contact lens detergents by the proposed method was in accord with its nominal concentration.