Flow Injection Determinations of Cobalt (II) and Iron (II) Based on Chemiluminescence Induced by the Catalytic Decomposition of Peroxomonosulfate

Abstract

The catalytic decomposition of peroxomonosulfate (PMS, KHSO₅) was found to be light-emissive and utilized for the chemiluminescent (CL) determinations of Co ( II ) and Fe ( II ) by a flow injection method. With the same flow system, Co ( II ) and Fe ( II ) were selectively determined under a neutral condition (pH 7) and an acidic condition (pH 2), respectively. By use of sensitizer, brilliant sulfoflavine in an octadecyltrimethylammonium chloride micellar solution, the CL signal was enhanced by 100-400 times and its linear dynamic range was extended over three orders of magnitude. The lower detection limits (S/N=3 ) were 5×10^-9 M for Co (II) and 6×10^-9 M for Fe (II) and the relative standar d deviations (n = 10, 100-μl injection of 1×10^-7 M sample solution) were 1.4% for Co (II) and 5.2% for Fe (II). The method was successfully applied to real samples. A brief explanation of the present CL reaction is also given.