Flow injection chemiluminescence determination of 2-methoxyestradiol based on inhibition of luminol-potassium ferricyanide reaction

Abstract

A novel flow-injection chemiluminescence (FI-CL) method is described for the determination of 2-methoxyestradiol (2-ME). The method is based on the inhibitory effect of 2-ME on the CL reaction of luminol and potassium ferricyanide in alkaline solution. Under optimal conditions, net CL intensity was proportional to 2-ME concentration in synthetic and mouse plasma samples. Corresponding linear regression equations were 8.0 x 10(-9) -1.0 x 10(-7) g/mL for synthetic samples and 2.0 x 10(-9) -1.0 x 10(-7) g/mL for plasma samples. Detection limit for synthetic samples and limits for quantification of plasma samples were 8.4 x 10(-10) g/mL (3σ) for synthetic samples and 4.0 x 10(-9) g/mL for mouse samples. A complete analysis was performed for 60 s, including washing and sampling, resulting in a throughput of ≈ 60/h. The proposed method was applied for the determination of 2-ME in synthetic and mouse plasma samples. Percentage recoveries were 101.0-102.8% and 98.0-105.0%, respectively. A possible mechanism responsible for CL reaction is proposed.