Determination Co2+ in vitamin B12 based on enhancement of 2-(4-substituted-phenyl)-4,5-di(2-furyl) imidazole and H2O2 chemiluminescence reaction

In this paper, three kinds of imidazole derivatives, 2-(4-methylphenyl)-4,5-di(2-furyl) imidazole (MDFI), 2-(4-nitrophenyl)-4,5-di(2-furyl) imidazole (NDFI), and 2-(4-tert-butylphenyl)-4,5-di(2-furyl) imidazole (t-BDFI) were synthesized. In an alkaline medium, the chemiluminescence (CL) reaction of imidazole derivatives with H2O2 has been investigated. It was also found that MDFI/H2O2 and t-BDFI/H2O2 systems gave strong CL. When Co2+ was added into the two CL systems, the CL intensity was remarkably enhanced. In the optimum conditions, the CL intensity is linearly related to the logarithm of concentration of Co2+. The linear ranges are 5 × 10−9–2.5 × 10−7 mol/L for MDFI/H2O2 system and 5 × 10−9–2.5 × 10−7 mol/L for t-BDFI/H2O2 system, and the corresponding detection limits are 1.2 × 10−9 mol/L and 1.1 × 10−9 mol/L, respectively. The method was applied to the determination of Co2+ in vitamin B12 injection. Furthermore, the CL mechanism was also discussed.

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► Imidazole derivatives chemiluminescence (CL) intensity enhancement by Co2+.
► CL properties of three kinds of imidazole derivatives were investigated.
► A defined experimental design in order to found optimized conditions.
► The determination of Co2+ in vitamin B12.