Selective determination of human immunoglobulin G by flow-injection chemiluminescence

A novel flow-injection chemiluminescence method was developed for the selective determination of human immunoglobulin G (IgG) in the presence of thiomersal by changing the flow rates of peristaltic pump. The study was based on the independence and additivity of the CL signals of human IgG and thiomersal in the galangin-potassium permanganate-polyphosphoric acid system. In meantime, two equations relating to the concentrations of mixing solutions of human IgG and thiomersal vs the CL intensity were established and solved, on the basis of which the content of thiomersal included in samples was simultaneously determined too. The enhanced CL intensity was in proportion to concentrations in the range 8.0 × 10(-7) to 8.0 × 10(-5)  g/mL for human IgG and 1.0 × 10(-7) to 2.0 × 10(-6)  g/mL for thiomersal with the detection limits of 5.0 × 10(-7)  g/mL for human IgG and 6.0 × 10(-8)  g/mL for thiomersal, respectively. The relative standard deviation for 1.0 × 10(-5)  g/mL human IgG was 0.8% and for 2.0 × 10(-7)  g/mL thiomersal it was 2.0% (n = 10). The proposed method was applied to determine three synthetic samples with recoveries of 91.5-109.5%. In addition, the possible chemiluminescence mechanisms are discussed as well.