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Paul A.,Indian Central Salt and Marine Chemicals Research Institute | Paul A.,Academy of Scientific and Innovative Research CSMCRI | Perween M.,Indian Central Salt and Marine Chemicals Research Institute | Perween M.,Academy of Scientific and Innovative Research CSMCRI | And 7 more authors.
Physical Chemistry Chemical Physics | Year: 2015

A specific and efficient hydrogen bonding interaction between cyanide and the HN-H [imidazole] in an aqueous medium has been utilized for the selective recognition of cyanide under physiological conditions. The possibility of utilizing such an interaction for developing any practical device for the specific detection of cyanide in an aqueous environment has not been explored to date. We now report a simple dip and read conductometric sensor for cyanide ions using a tailored electrode in aqueous media. The purpose built reagent, 2-phenyl-1H-anthra-[2,3-d]-immidazole-5,10 dione was immobilized in a polyaniline matrix to fabricate this conductometric device. The homogeneous immobilization of the receptor in polyaniline was confirmed by FT-IR mapping. The proposed transduction mechanism is charge neutralization on the polyaniline moiety, which ultimately inhibits the protonation resulting in a decrease in the conductance of polyaniline. The sensor response was measured in three ranges of cyanide concentration (10-10 M to 10-8 M; 10-8 M to 10-6 M and 10-6 M to 10-3 M). Whereas the device is found insensitive in the first range, it acts as a detector in the second range and as a proportional sensor in the third range. The minimum detection limit of this device was found to be 10 nmol L-1 (2.6 ppt), which is significantly less than the WHO guideline values. The responses have been investigated under various conditions such as different pH and the electrochemical state of the polymer. The current device has been found to be better close to neutral pH and at a 400 mV vs. Ag/AgCl potential. The reproducibility and repeatability of the sensor was investigated and interference studies were performed. This journal is © the Owner Societies. Source

Maity D.,Indian Central Salt and Marine Chemicals Research Institute | Gupta R.,Indian Central Salt and Marine Chemicals Research Institute | Gupta R.,Academy of Scientific and Innovative Research CSMCRI | Gunupuru R.,Indian Central Salt and Marine Chemicals Research Institute | And 5 more authors.
Sensors and Actuators, B: Chemical | Year: 2014

Tailored calixarene derivative has been synthesized by incorporating dithiocarbamate unit, which has been anchored on the surface of the gold nanoparticles. Gold nanoparticle is a specific class of colorimetric transducer exhibiting intense red colour due to SPR absorbance. Anchoring of calixarene on to the surface of the gold nanoparticles has been confirmed by IR, UV-vis, TEM and EDX analysis. The interaction of this new material with various metal ions has been investigated and it exhibited distinct colour change from pink to blue, detectable even by naked-eyes, in presence of Co(II) ion. Binding of Co(II) is confirmed by clustering of gold nanoparticle as observed under TEM as well as DLS study. The detection limit for metal ion obtained by colorimetric method is 10-9 M. The same material has also been used for electrochemical sensing of Co(II) in aqueous media where amperometric response due to binding of metal ion has been investigated. The calixarene functionalized gold nanoparticles was immobilized in a conducting polymer (polyaniline) matrix. In this method, a detection limit of 10-12 M for Co(II) has been achieved. Competitive sensing study revealed no significant interference from other metal ions used in this study in both the sensing methods. © 2013 Elsevier B.V. All rights reserved. Source

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