Piezoelectric quartz crystal (PQC) with photochemically deposited nano-sized Ag particles for determining cyanide at trace levels in water

A sensitive and cost-effective cyanide sensor has been developed based on piezoelectric quartz crystal (PQC) for determining cyanide at trace levels in water. The sensing layers were fabricated by depositing photochemically generated nano-sized silver particles on titanium dioxide film at the electrode surface of PQC. The freshly produced metallic Ag interacts strongly with cyanide, leading to improved sensor performance (3 times higher sensitivity and 12 times lower detection limit as compared to the bulk Ag-coated PQC). The linear working range was over three orders of concentration from 0.1–10 μmol/L. Under the optimized conditions for photochemical deposition of nano-sized Ag with controlled TiO2 film thickness and desired silver particles in nano-sized range, factors affecting its analytical application such as background buffer, solution pH and potential interferents were investigated. Satisfactory recovery at 98.8% and good repeatability (R.S.D. for n = 3) at 3.19% were obtained in spiked cyanide concentration from 0.013–0.233 mg/L. The procedure was shown able to provide a reliable method for quantitative determination of cyanide at more than 30 times lower than the World Health Organization (WHO) guideline value for drinking water.