Iodophenol blue-enhanced luminol chemiluminescence and its application to hydrogen peroxide and glucose detection

Abstract

In this study, we found that iodophenol blue can enhance the weak chemiluminescence (CL) of luminol–H2O2 system. With the aid of CL spectral, electron spin resonance (ESR) spectral measurements and studies on the effects of various free radical scavengers on the iodophenol blue-enhanced luminol–H2O2 system, we speculated that iodophenol blue may react with H2O2 and oxygen to produce oxidizing radical species such as OH• and O2•− resulting the formation of 1O2. The generated 1O2 may react with luminol anion generating an unstable endoperoxide and subsequent 3-aminophthalate* (3-APA*). When the excited-state 3-APA returned to the ground-state, an enhanced CL was observed. Based on the H2O2 concentration dependence of the catalytic activity of iodophenol blue, a cheap, simple, sensitive CL assay for the determination of H2O2 was established. Under the optimum experimental conditions, a linear relationship between the relative CL intensity and H2O2 concentration in the range of 0.025–10μM was obtained. As low as 14nM H2O2 can be sensitively detected by using the proposed method. The relative standard deviation for 5, 1 and 0.25μM H2O2 was 2.58%, 5.16% and 4.66%, respectively. By combining the glucose oxidase (GOx)-catalyzed oxidation reaction, CL detection of glucose was realized. The linear range of glucose detection was 0.1–30μM with a detection limit of 0.06μM. The proposed method has been applied to the detection of glucose in diluted serum.