A new microfluidic polymer chip with an embedded cationic surfactant ion-selective optode as a detector for the determination of cationic surfactants

A new microfluidic polymer chip with an embedded cationic surfactant (CS) ion-selective optode (CS-optode) as a detector of flow-injection analysis (FIA) for the determination of CSs was developed. The optode sensing membrane is based on a poly(vinyl chloride) membrane plasticized with 2-nitrophenyl octyl ether containing tetrabromophenolphthalein ethyl ester. Under the optimal flow conditions of the FIA system, the CS-optode showed a good linear relationship between the peak heights in the absorbance, and the concentrations of CS in a concentration range from 50 to 400 μmol dm^-3. The sample throughput of the present system for the determination of a CS ion (300 μmol dm^-3 zephiramine) was ca. 11 samples h^-1. The proposed FIA system was applied to determine the level of CS in dental rinses.