Design of an Optical Nanosensor for Determination of Trace Amounts of Thiourea and Cyanide

Abstract The characterization of an optical absorption-based one-shot sensor is described for the determination of thiourea and cyanide ions based on the immobilization of new nanocomposite of MWCNT- graft -poly(citric acid)/Au on a triacetylcellulose membrane. MWCNT-g-PCA/Au is covalently bonded to a transparent triacetylcellulose film. Thiourea and cyanide ions react with the immobilized nanocomposite and cause a decrease in the absorbance of the film at 300 nm. The response time of sensing phase is within 5 min depending on the concentration of thiourea and cyanide. This sensing phase has a linear range of 40–250 and 250–1000 mg L − 1 for thiourea with a limit of detection of 11 mg L − 1 at a wavelength of 300 nm. This sensing phase has a linear range of 0.1–200 mg L − 1 for CN − ions with a limit of detection of 0.08 mg L − 1 at a wavelength of 300 nm. The nanosensor was successfully applied for the determination of thiourea and cyanide in tap and spring water.