A colorimetric and fluorescent dual-channel cyanide ion probe using crosslinked polymer microspheres functionalized with protonated Brooker's merocyanine

This paper describes the development of a colorimetric and fluorescent cyanide probe based on crosslinked polymer microspheres functionalized with a protonated merocyanine. The functionalised microspheres were prepared by free radical polymerization using 4-((E)-2-[(4-hydroxylphenyl) ethenyl-1-allyl pyridinium bromide as the functional monomer, ethylene glycol dimethacrylate as the crosslinker, and azobisisobutylnitrile as the radical initiator. Upon introducing CN⁻ to a suspension of the functionalised microspheres in ethanol/H₂O (9:1, v/v), a change from yellow to red and a decrease in fluorescence intensity at 497 nm were immediately observed. This CN⁻ probe can be reversed many times, which is cost efficient and beneficial to the environment. Analytical application of the functionlised microspheres to measure CN⁻ concentration in spiked water samples was explored with good recoveries. Thus, the colorimetric and fluorescent CN⁻ probe has high potential for the ultrasensitive detection of CN⁻ in real samples. Copyright © 2015 Elsevier Ltd.