Finding and identifying blood

To quickly find out if a suspicious stain on an object or fabric is consistent with blood, several tests can be used. These tests make use of color reactions that are catalyzed by blood. They do not differentiate between human and animal blood, however, and false positives are possible.

With Hemident, a (clean) cotton swab is rubbed firmly over the suspicious stain. The head of the cotton swab is then inserted in the test-tube and the shaft broken, so that the cotton falls into the tube. After replacing the cap of the Hemident tube, the bottom ampoule is crushed, and then the ampoule in the cap. The presence of blood is indicated by a blue-green discoloration on the cotton, at the spot that was in close contact with the stain (see photo at left).
 

For the use of Hemastix, a drop of water is applied to the suspicious stain. After a few moments (to allow some of the blood to dissolve), the reactive area at one end of the strip is brought in contact with the water. A green coloration of the test surface is indicative for the presence of blood.

With Peroxtesmo, the material to be tested is wetted with water or physiological saline solution and allowed to soak for about 1 minute. The exposed test strip is then applied to the wet area. A blue color is indicative for the presence of peroxidase, an enzyme present in blood.

Cat. No. F-62100
Hemident, 10 test units in a box, based on MacPhail's reagent.

Cat. No. F-82300
Hemastix, package of 50 tests (8 cm long strips with a reactive area of 5 x 5 mm at one end).

Cat. No. M-40900
Peroxtesmo, package of 25 tests. The test papers of 15x30 mm are sandwiched between an adhesive tape and a plastic bottom sheet.
 

To find blood traces, even outside or in a room that has been cleaned, luminol is very useful. The three solutions in this set are mixed before use and diluted with 700 ml of distilled water to provide 1 liter of working solution.
The working solution (which can be used for only a couple of hours after mixing) is sprayed on the area that has to be examined.

Blood traces, even very diluted ones, cause the luminol and the hydrogen peroxide in the solution to react with each other. This reaction is unique, in that it releases (white-green) light. The reaction lasts several minutes and can even be photographed (in complete darkness) or taped on video (using a light amplifier or "night vision equipment" connected to the video camera).
The solution causes blood traces to run.

F-30000
Luminol set, three (water-based) solutions that will provide 1 liter of ready-to-use solution after mixing and dilution with water.