This invention relates to a method of detecting the presence of bisulfite ions in a sample.  A solution containing silver nanoparticles coated in a conjugate of diamine tetra sulphonato calix[4]arene changes its colour from orange yellow to bright orange red immediately in the presence of HSO3- ions

Indian patent application no. 1089/MUM/2011

Inventors: C P Rao, Amitabha Acharya