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Fluorescein and its derivatives: New coreactants for luminol chemiluminescence reaction and its application for sensitive detection of cobalt ion

Zhou, Yang, Du, Jianxiu, Wang, Zhen
Talanta 2019 v.191 pp. 422-427
chemiluminescence, cobalt, detection limit, fluorescein, silica gel
Fluorescein and its derivatives, including 4′,5′–dibromofluorescein, 2′,7′–dichlorofluorescein and 2′,4′,5′,7′–tetrabromofluorescein can be employed as efficient coreactants for luminol reaction. Under an alkaline condition they reacted with luminol to produce measureable chemiluminescence (CL) in the absence of any extra–oxidant. Cobalt ion (Co²⁺) significantly enhanced the CL emission of the reaction. The CL emission was strongly dependent on the concentration of carbonate buffer used; higher concentration of carbonate buffer provided more intense CL emission. The system had two emission peaks locating at 425 nm and 535 nm, respectively. With 4′,5′–dibromofluorescein as the coreactant for luminol reaction, a new CL method was developed for the detection of Co²⁺. The procedure allowed the linear detection of Co²⁺ in the range of 5–1000 nmol/L. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.8 nmol/L and 5.0 nmol/L, respectively. The intra–day precision (n = 11) and inter–day precision (n = 3) was 3.2% and 4.7% for replicated measurements of 0.2 μmol/L Co²⁺ solution. The method was successfully applied to the determination of Co²⁺ in blue silica gel samples.