Potentiometric determination of cetylpyridinium chloride in oral desinfectants by flow injection analysis

• Main Author: Baptista, Paula
• Publication Date: 2003
• Other Authors: Araújo, Alberto N., Montenegro, Maria da Conceição B.S.M.
• Format: Article
• Language: por
• Source: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Download full: http://hdl.handle.net/10198/938
• topic: Potentiometry; Oral disinfectants; FIA; Ion-selective electrodes; Cationic surfactants; Spectrophotometric determination; Pharmaceutical preparations; Capillary electrophoresis; Pair extraction; Construction; Titrations; Sensor

The work describes a new procedure for cetylpyridinium chloride determination in oral disinfectants, based on a flow-injection system with potentiometric detection. The determination was based on the measurement of picrate concentration decrease as result of ion-pair reaction with the analyte present in the injected sample. In the optimised set-up the sample injection volume was kept at 400 µL and merged downstream with the reagent solution containing 1,0 x10-5 mol/L of picrate adjusted to pH 5.0 with citrate/citric acid buffer. The flow rate was fixed at 8 mL/min and the reactor length at 40 cm. The proposed procedure enables the determination of cetylpyridinium in the analytical range of 5,0x10-6 – 7,5x10-5 mol/L at a sampling rate of 60/h. The results for real samples had a precision better than 3% and were comparable to the labelled values.