Malachite Green
Definition
A synthetic triphenylmethane dye with an intense blue-green colour in its oxidised form. It is a common industrial dye and the coloured product of a positive LMG blood test.
- Chemical class
- Triphenylmethane dye
- Oxidised colour
- Intense blue-green
- Common non-forensic use
- Industrial and textile dye
- Forensic use
- Colour product of a positive LMG blood test
Common questions
How is malachite green related to the leucomalachite green blood test?+
Leucomalachite green is the colourless reduced form of malachite green; reaction with hemoglobin's peroxidase-like activity oxidises it back to malachite green, producing the visible blue-green colour that signals a presumptive positive.
Does a malachite green colour change confirm the presence of human blood?+
No. Like most presumptive blood tests, a positive colour change indicates possible blood but can be triggered by other oxidising substances, so a confirmatory test is needed to establish the stain is actually human blood.
Related terms
- Cross-Checking
- The practice of running two different presumptive tests on adjacent cuttings from the same stain. Concordant results (both positive or both negative)...
- Leucomalachite Green (LMG)
- The reduced, colourless form of malachite green. It is oxidised to the coloured malachite green form by active oxygen released when haemoglobin...
- Presumptive Colour Test
- Any rapid field or laboratory test that produces a colour change in the presence of a target substance. Positive results are indicative,...
- Substrate Control
- A sample of the unstained surface material from an area adjacent to a body fluid stain, collected alongside the stain and processed...
- Triphenylmethane Dye
- A class of synthetic dyes built around a central carbon bonded to three phenyl groups. Members include malachite green, crystal violet, and...