66 μl nitroblue tetrazolium (NBT) stock
33 μl 5-bromo-4-chloro-3-indolyl galactopyranoside (BCIP) stock
10 ml color development buffer
Both NBT and BCIP stocks are 50 mg/ml in dimethylformamide. NBT stock is made by suspending 50 mg NBT in 700 ml dimethylformamide. Vortex. Add 300 μl distilled water to dissolve. Store both stocks at 4ºC in dark.