A green stability indicating ISE-potentiometric method for the monitoring of chlorhexidine in the presence of its rapidly absorbed toxic degradation product; a kinetic study

Abstract

Chlorhexidine (CHX) is an antiseptic and disinfectant used in several antimicrobial preparations. In the current study an environmentally friendly ISE-potentiometric method was developed for the determination of CHX, measurements were carried out directly in the aqueous solution of the sample without pretreatment. Four PVC-membranes were fabricated using dioctylphthalate as a solvent mediator along with different cation exchangers, namely; sodium tetraphenylborate, sodium phosphotungstate tribasic, sodium phosphomolybdate and ammonium reineckate. Responses were compared and that containing ammonium reineckate illustrated the best near-Nernstian slope through a wide linear range (3.85 × 10−6–1 × 10−3 M). The sensor was able to determine CHX in colored and turbid solutions without prior extraction, pretreatment, filtration or derivatization steps. This method enabled in-site stability study without interference of para-chloroaniline (PCA) the most common and carcinogenic degradation product by monitoring the degradation kinetics of CHX at different pH values (3.5, 4.0 and 5.0). The sensor was able to provide a reliable in-line monitoring of the process without the need for frequent sample withdrawal at time intervals or sample pretreatment steps which saved time. Sensor response characteristics were calculated according to the IUPAC recommendations and the method was validated as per the ICH recommendations. The proposed method provided a green eco-friendly method that saves cost, time and effort, and consumes the least amount of chemicals.