Sequential injection analysis of thiocyanate ions using a microfluidic polymer chip with an embedded ion-selective electrode

A sequential injection analysis (SIA) system for the determination of SCN- ion using a microfluidic polymer chip with an embedded SCN-ion-selective electrode (SCN--ISE) as a detector was developed. Under the optimal flow conditions of the SIA system, the SCN-ISE showed a good linear relationship between peak heights and logarithmic concentrations of SCN-ion with a Nernstian slope of 59.4 ± 3.8 mV decade^-1 in a concentration range from 1.0 × 10^-5 to 1.0 × 10^-1 mol dm^-3. Sample throughput of the present system for the determination of SCN- ion was approximately 12 samples h^-1. The proposed SIA system was applied to the determination of the level of SCN- ion in human saliva samples.