An Ammonia Sensor Using an Unadorned Bromocresol Layer

ABSTRACT

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 λ_max for the neutral (acid) form of the BCP was found to be 435 nm and the λ_max 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.

KEYWORDS:

• Ammonia sensor
• bromocresol purple
• acetate sheet
• colorimetric sensor

Acknowledgments

M.Akdağ thanks the European Commission for an Erasmus scholarship

Disclosure statement

There is no conflict of interest