Analysis of complex mixtures:

The presence of heavy atoms such as, iodine, silver, lead, etc. in the sample or in the solid matrix is found to improve the sensitivity of the methods and helps in the analysis of complex mixtures through RTP. The presence of a heavy atom is an important factor for RTP detection because this kind of atom favors the intersystem crossing from the singlet state to the triplet state of the guest. The analyte, the cyclodextrin or other matrix and the component holding the heavy atom form a ternary complex that gives adequate protection from quenching and constitutes a feasible approach for enhancing the phosphorescence emission in solution. The inclusion of the heavy atom in a separate molecule makes it probable to excite phosphorescence from molecules contain just carbon, hydrogen, oxygen and nitrogen.

Presently, it has been reported that RTP could be observed in solutions without the use of an organized medium. Within this method, a significant amount of a heavy-atom salt like potassium iodide and thallium (I) nitrate along with sodium sulfite is added to the analyte. The sodium sulfite acts as an oxygen scavenger. The RTP emission is a consequence of intermolecular protection and is refered to heavy-atom-induced RTP (HAI-RTP).