Analytical Sciences

Sequential Injection Analysis of Thiocyanate Ions Using a Microfluidic Polymer Chip with an Embedded Ion-Selective Electrode

Benjaporn TOSSANAITADA,* Takashi MASADOME,* and Toshihiko IMATO**

*Department of Applied Chemistry, Faculty of Engineering, Shibaura Institute of Technology, Toyosu, Koto, Tokyo 135-8548, Japan
**Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka 819-0395, Japan

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.

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