Hello, see attached info may be useful for you.

Good luck!

Hi! I used this one successfully for measurement of SOD IN GEL activity

http://www.bio-protocol.org/e811

Threre is also a way to measure IN VITRO activity, its also worked for me

https://ejournal.sinica.edu.tw/bbas/content/1996/2/bot372-03.pdf

"Spectrophotometric assay of SOD activity was carried out by adapting the procedure of Oberley and Spitz (1985). For a 20-cuvette assay, the following reagents were added to a test tube: 13.8 ml of 50 mM potassium phosphate buffer (pH 7.8) containing 1.33 mM DETAPAC; 0.5 ml of 2.45 mM NBT; 1.7 ml of 1.8 mM xanthine. The total volume was 16 ml, enough to dispense 0.8 ml into each of the 20 cuvettes.

Cuvette holders in the sample chamber of the spectrophotometer were thermo-controlled at 25°C. For the blank test, 100 ml of 50 mM potassium phosphate buffer (pH 7.8) was added into a cuvette with 0.8 ml of working solution. A suitable concentration of xanthine oxidase was diluted, and 100 ml of it was added into the cuvette to initiate the reaction. A linear curve with a slope of 0.025 absorbance per min in time scan was obtained by adjusting the concentration of xanthine oxidase. The time scan lasted 5 min. The phosphate buffer was then replaced by a serial dilution of a SOD sample to obtain different decreased slopes, and each reaction was performed at least twice. At least three dilutions of a SOD sample were scanned in the defined reaction, one for the maximum competition (i.e., the lowest slope that could be obtained by adding the sample into the reaction), the other two were diluted to approach half of the maximum competition. The slope-sample amount data were then converted to a plot of slope against sample amount. Maximum competition (lowest slope) and a linear curve, including the point for the blank test, were the two elements in the plot. A regression function was obtained for the linear curve. The sample amount corresponding to half of the lowest slope was obtained through interpolating or extrapolating to the regression curve. One unit of SOD activity was defined as the amount of SOD which produced one half of the maximum competition against NBT in the specified system."

i hope this research article help you out.

Have a look on DOI:http://dx.doi.org/10.7314/APJCP.2012.13.6.2571 Superoxide Dismutase Isoenzyme Activities in Plasma & Tissues of Breast Cancer Cases

Asian Pacific J Cancer Prev, 13, 2571-2576