Design a optical sensor based on incorporation of ninhydrin in sol-gel matrix for determination of cyanide

We herein describe the fabrication of a ninhydrin (NH) incorporated sol-gel glass with nanoporous structure as an optical sensor to measure cyanide ion. Tetraethyl orthosilicate was used as precursor to form the porous polymeric network for entrapment of NH in porous silica gel matrix. Our thorough experimental-based results revealed that the porous feature of the matrix as well as its average pore size could play significant roles in almost all critical parameters, affecting the sensor performance, including sensitivity, selectivity and response time of sensor. The constructed sensors showed optimum performance under the working conditions, including water: alkoxide ratio of 4:1, water acidity of 0.1 M and ethanolic solution of NH 0.112 mol L-1. Under optimum conditions, a linear calibration curve over the range 0.003 to 5.000 μg mL−1 (1.15×10-7 – 1.91×10-4 mol L-1) of cyanide ion was obtained, along with a detection limit value of 0.0013 μg mL−1 (4.99×10-8 mol L-1). Meanwhile, the sensor exhibited excellent RSDs for both intra-day and inter-day precision.