An intense blue/green color reaction in 3 seconds is presumptive evidence that blood is present. Leuco-malachite green has long been a favorite of field investigators because of its high sensitivity (1:300,000).
LMG formulation: 0.2 g of leucomalachite green dissolved in 67 mL of methanol using a clean, dry, glass beaker. Add 33 mL of glacial acetic acid and 0.67 g of sodium perborate and then the solution is stirred using a magnetic stirrer until the LMG had completely dissolved. 300 mL of HFE 7100 is finally added and the solution stirred. The resulting solution isstored in a dark coloured glass bottle and applied by spraying with a Preval® sprayer.
LMG is a known Carcinogen. Must be used with appropriate respirator, gloves and eye protection.