How good is Pico-Green Dye ?

ethidium bromide is good for that, it is an intercalating agent used as a fluorescent tag (nucleic acid stain) in molecular biology laboratories for techniques such as agarose gel electrophoresis. It is commonly abbreviated as "EtBr"but it should be handled carefully because it may be a carcinogen or mutagen

otherwise you can use PAGE with silver staining

Thank you for your answer Mr. Mohammed Alhomidi.

I've used anti oxodG antibody to monitor mtDNA mutation in real time. Can try this.