Flow-injection chemiluminescence of the luminol-potassium periodate system enhanced by TGA-capped CdTe quantum dots for the determination of theophylline.

The chemiluminescence (CL) behaviour of the luminol-potassium periodate system enhanced by CdTe quantum dots capped with thioglycolic acid (TGA-CdTe QDs) was studied using kinetic experiments, CL spectra, UV-vis absorption spectra and fluorescence spectra. The production of oxygen-containing reactant intermediates (O2 •- and OH• ) in the present CL system was verified by CL. The possible CL mechanism was discussed in detail. Furthermore, theophylline (THP) was determined based on its enhancement of the CL intensity of the CdTe QDs-luminol-potassium periodate system coupled with a flow-injection technique. Under these optimized conditions, the linear range was found to be from 1.0 × 10-8 to 1.0 × 10-5  g/mL with a detection limit of 2.8 × 10-9  g/mL (3σ). The recoveries for the determination of THP in tablets were from 98.2 to 99.6%.