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.