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1.4 CHEMICAL SCIENCES, Analytical chemistry

Publication Details

International Journal of Environmental Analytical Chemistry, August 2020.


Bromocresol Purple,(BCP) cast onto an acetate sheet, was used to sense ammonia. This simple layer responded reversibly to a low concentration ( 15 ppm) of ammonia in the presence of water vapour. The BCP solution was spincoated on an acetate sheet from a solution in dichloromethane. This layer was exposed to nitrogen and NH3/H2O vapour in quick succession. The colour change occurred from yellow to purple rapidly in the solid state. The λmax for the neutral ( acid) form of the BCP was found to be 435 nm and the λmax for the dianion ( base form) of the BCP was found to be 610 nm A mechanism previously predicted theoretically was confirmed using FTIR identifying the presence of a peak associated with a carbonyl in the dianion form.