Detection of biothiols in human serum by QDs based flow injection “turn off–on” chemiluminescence analysis system

In the present work, a flow injection (FI) “turn off–on” chemiluminescent method was developed for the determination of glutathione (GSH). Strong chemiluminescence (CL) signals were observed from the hydrogen peroxide and CdTe quantum dots (QDs) system under basic condition, addition of trace amount of Cu(Ⅱ) could caused significant CL quenching of the CdTe QDs–H2O2 system. In the presence of biothiols, Cu(Ⅱ) can be removed from CdTe QDs surface via forming Cu(Ⅱ)–S bond with thiols, and the CL signal of CdTe QDs–H2O2 system was recovered. Thus, the CL signals of CdTe QDs–H2O2 system were turned off and on by the addition of Cu(Ⅱ) and biothiols respectively, and a flow injection CL analysis system for the determination of biothiols was established. Under the optimum conditions, the CL intensity and the concentration of GSH have a good linear relationship in the range of 2.0×10−9−6.5×10−7 mol L−1 (R2=0.9993). The limit of detection for GSH is 1.5×10−9 mol L−1 (S/N=3). This method has been applied to detect GSH in human serum with satisfactory results.