A Novel Optical Sensor for Determination of Thiocyanate

Abstract

A novel optical sensor (optode) is described for the determination of thiocyanate using methyltrioctylammonium chloride immobilized on triacetylcellulose membrane. The response to thiocyanate is the result of adsorption of [Co(SCN)₄]²⁻ on sensing membrane, which caused the colorless membrane to change to blue. This optode can readily be regenerated by using 0.02 mol/l sodium oxalate solution. The linear range of the method was 3.44×10⁻⁵ to 8.61×10⁻⁴ mol/l of thiocyanate with a limit of detection 1.51×10⁻⁵ mol/l. The relative standard deviation for eight replicate measurements of 8.61×10⁻⁵ and 4.30×10⁻⁴ mol/l of thiocyanate was 3.45 and 1.23%, respectively. The sensor was successfully applied for the determination of thiocyanate in saliva of smokers, nonsmokers and various water samples.

Keywords:

• Optical sensor
• thiocyanate
• methyltrioctylammonium chloride
• triacetylcellulose

The authors are grateful to Shahid Chamran University Research Councils for financial support.