Substrate control
Definition
A test of the same material (fabric, surface, soil) at an area that shows no visible staining. A positive substrate control indicates the material itself contains something that drives the colour change, making the test on the stained area equivocal.
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...
- Malachite green
- A synthetic triphenylmethane dye with an intense blue-green colour in its oxidised form. It is a common industrial dye and the coloured...
- 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,...
- Triphenylmethane dye
- A class of synthetic dyes built around a central carbon bonded to three phenyl groups. Members include malachite green, crystal violet, and...
Explained in
- Leucomalachite Green TestA test of the same material (fabric, surface, soil) at an area that shows no visible staining. A positive substrate control indicates the material itself conta...