Determination of zinc (II) using the micellar enhanced chemiluminescence of 1, 10-phenanthroline

Abstract

A flow-injection analysis technique along with chemiluminescence detection was investigated to determine small amounts of zinc ions by means of the 1, 10-phenanthroline-hydrogen peroxide-sodium hydroxide system containing trimethylstearylammonium chloride (TSAC). This chemiluminescence method was based on the following chemical reaction: the superoxide ion (anion radical) reacts with 1, 10-phenanthroline to form a 1, 2-dioxetane derivative intermediate, which emits chemiluminescence by way of a excited 3, 3'-diformyl-2, 2'-dipyridyl. Among the examined cationic surfactants, TSAC provided the highest enhancement of the CL intensity, approximately 90- times higher than that in the absence of surfactants. The limit of the determination for Zn(II) was 2.3 × 10^-8 mol/l (200 × 10^-6l sample injection) under the optimum conditions. Furthermore, in the presence of 2, 2'-bipyridine, the CL intensity was enhanced nearly 5- times higher than that under the conditionsΔwithout 2, 2-bipyridine. The authors investigated the mechanism of CL enhancement by spectro-photometry. The role of 2, 2'-bipyridine was revealed through the 3-dimensional spectra of Zn(II)-1, 10-phenthroline complex formation; that is, 2, 2'-bipyridine enhanced the rate of chelate formation on the Zn(II)-1, 10-phenanthroline complex, which was needed to produce the super oxide ion (anion radical). As a result, 2, 2'-bipyridine increased the amount of super oxide ion (anion radical) and the chemiluminesence was enhanced.