Blue has a wavelength of around 480 nm and will make your sample visible. If your sample is too concentrated you can dissolve it in water.
Blue Substrate
The volume (ml) in milliliters of buffered % w/v solutions at the medium pH are also used for DNA extraction Organic (Phenol-Chloroform) Extraction, Non-Organic (Proteinase K and Salting out), Chelex (Ion Exchange Resin) Extraction, EDTA or PBS aqueous.