Component	Volume per sample	Final Concentration
X-gal in dimethylformamide (20 mg/mL)	1 mL	1 mg/mL
Citric acid/sodium phosphate buffer, pH = 6.0 (0.2 M)	4 mL	40 mM
Potassium ferrocyanide (100 mM)	1 mL	5 mM
Potassium ferricyanide (100 mM)	1 mL	5 mM
Sodium chloride (5 M)	0.6 mL	150 mM
Magnesium chloride (1 M)	40 μL	2 mM
Water	12.4 mL
Total	20 mL