Luminescence Determination of Dopamine Using a Photocamera

The study demonstrates that the interaction of dopamine with fluorescamine can serve as a basis for a fluorescence assay for dopamine using a camera, as the product formed in this interaction exhibits a fluorescence peak in the visible spectral region (485 nm). Fluorescence can be excited with a light-emitting diode emitting in the near-ultraviolet spectral region (395 nm). The reaction should be carried out at pH 8–8.5 in a phosphate buffer solution for 5 min, with fluorescamine being added to the reaction mixture last. The performance characteristics of the camera-based assay were evaluated and compared with those of a similar dopamine assay using a professional spectrofluorometer and a spectrophotometer. The limits of detection for dopamine using a camera, a spectrophotometer, and a spectrofluorometer were 1.8, 1.6, and 0.5 µM, respectively, while the analytical ranges were 5.4–50, 4.8–100, and 1.5–100 µM. The presence of common inorganic ions in concentrations 10 times higher than that of dopamine does not interfere with the assay. The proposed method for dopamine determination can be used for the quality control of pharmaceutical products.