A Sensitive Electrogenerated Chemiluminescence Assay For Determination of Melanin in Natural and Biological Samples

A rapid, simple and highly sensitive flow-injection (FI) electrogenerated chemiluminescence (ECL) method was developed for the determination of melanin, a biological pigment present in the skin, eyes, hair, scales and it is responsible for color of them. The proposed method was based on the ECL reaction of Ru(bpy)32+ with melanin in an acidic medium. The different experimental parameters affecting the ECL intensity were carefully studied and incorporated into the procedure. The method permits the determination of 0.01 - 2.0 μg mL-1 and 3.0 - 35 μg mL-1 of melanin with correlation coefficients (r) > 0.9999. The lower limit of detection (LOD) is 0.0005 μg mL-1 (S/N = 3) and the lower limit of quantitation (LOQ) is 0.01 μg mL-1. The proposed method was successfully applied to the determination of melanin in Sepia Officinalis and natural samples.