Determination of Cytochrome <Emphasis Type="Italic">c</Emphasis> in Human Serum and Pharmaceutical Injections Using Flow Injection Chemiluminescence

It was found that the complex of cytochrome c (Cyt c) and hydrogen peroxide could significantly catalyze the chemiluminescence (CL) reaction from luminol–hydrogen peroxide, and a sensitive, rapid, and simple CL procedure was proposed for the determination of Cyt c in a flow injection system for the first time. The increment of CL intensity was linear over the concentration of Cyt c ranging from 5 to 700 ng ml⁻¹, with a detection limit of 2 ng ml⁻¹ (3σ). At a flow rate of 2.0 ml min⁻¹, a complete analytical process could be performed in 30 s with a relative standard deviation of less than 4.0%. The proposed method was applied successfully for the assay of Cyt c in pharmaceutical injections and human serum, and the recoveries were from 98.0% to 108.8% and 92.5% to 109.0%. The possible mechanism of Cyt c enhanced CL reaction was also discussed.