I am carrying out the tyrosinase activity of various essential oils taking L-Dopa as a substrate. I need to know the required concentration of the substrates and the other reagents used in this method. However, there are very few articles or reports that use different wavelengths, such as 475nm and 490-492nm. So, does anyone know what the difference between these two wavelengths is, and why some people use 490-492nm instead of 475nm (the standard wavelength for dopachrome)? How long the prepared working solution (L-Dopa) be kept unused?