Development of Environmentally Friendly Chemical Sensor for Detection of Cyanide in Water

Abstract

A rapid quantitative colorimetric determination of CN was developed by synthesizing BF2-curcumin reagent. Borontriflouride was added to the carbonyl group of curcumin, an extract from turmeric. Parameters affecting to the synthesis and reaction products were optimized. The optimum parameters were found to be 1 mM BF2-curcumin concentration, sample pH of 9 and 5 minutes reaction time. The reagent was synthesized within a micro tube to which the sample can easily and directly be added for an in-tube detection. The reaction mechanism with cyanide relied on the deprotonation of the hydroxyl group of BF2-curcumin. The orange-red color of BF2-curcumin solution changed to blue upon reaction with cyanide solution. Tapioca flour was used as polymeric material in which the reagent was embedded. Parameters affecting to the synthesis of the BF2 curcumin synthesized starch film were also optimized. An innovative free of charge application installed on a mobile phone was used to capture and measure the color intensity of the reaction product. A digital image analysis was applied to the reaction product to obtain analytical data in the form of Red Green Blue (RGB) values. Quantification was achieved by exploiting the relationship between RGB value and concentration of colorimetric product. A considerably lower detection limit (0.12 + 0.007) and (0.40 ± 0.021) were obtained for the reagent and sensor analysis respectively. An efficient linear range (0.27 mg/L) and good sensitivity were achieved. The method validation point out good intra- and inter-day precision for both the reagent and the synthesized starch film. Accuracy of the developed method was excellent in analytical performances. Water sample from an abandoned tin mine site were analyzed using the sensor and the results were in good agreement with spectrophotometer analysis.