This method allows selective staining and quantification of DNA in gels by soaking the gel in a SYBR Green I/Nitro Blue Tetrazolium solution and then exposing it to sunlight or a blue light source. This produces a visible precipitate and requires almost no equipment, making it ideal for field use.
Paredes, A. J., Alfaro-Valdés, H. M., Wilson, C. A. DNA Staining Method Based on Formazan Precipitation Induced by Blue Light Exposure. J. Vis. Exp. (131), e56528, doi:10.3791/56528 (2018).