If you use the method of NBT, you don´t need to expose to UV, white light is enought to carry out the reaction and you need to make some sample dilutions to make the standard (see attachment, in spanish)
The way which we followed in our researches on SOD is illustrated in one of our publication on this enzyme
Asian Pacific Journal of Cancer Prevention, Vol 13, 2012 2571 " Superoxide Dismutase Isoenzyme Activities in Plasma and Tissues of Iraqi Patients with Breast Cancer"