Luminol/CdTe quantum dots/sodium periodate system in conjunction with response-surface methodology for chemiluminometric determination of some tetracyclines

Abstract

A simple and sensitive chemiluminometric method is described for the determination of tetracycline (TC) and oxytetracycline (OTC) in their hydrochloride form on the basis of drastic enhancement of the chemiluminescence (CL) from the luminol/L-cysteine-capped CdTe quantum dots (QDs)/sodium periodate system, caused by the presence of TC and OTC hydrochloride. The method uses pH value at which tetracyclines have proven to be stable. Response surface methodology was exploited for optimizing the experimental conditions. The synthesized QDs were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy, and photoluminescence spectroscopy. A possible mechanism of the CL system was proposed based on the CL spectra and the effect of some specific radical-scavengers on the system. Under the optimum conditions linear dynamic ranges of 5.0×10−8–6.0×10−6molL−1 and 5.0×10−8–8.0×10−6molL−1 were observed for TC and OTC, respectively with corresponding detection limits of 2.2×10−8molL−1 and 3.0×10−8molL−1. The precision (RSD%) for five replicate determinations of TC and OTC were respectively no more than 3.4% and 4.0%. The method was satisfactorily applied to the determination of TC.HCl and OTC.HCl in water samples, pharmaceutical formulations, and honey.