Manufacturer: Bluestar

HEXAGON OBTI is the perfect complement to BLUESTARŽ FORENSIC. This rapid screening test presumes that a bloodstain is of human origin. This helps the investigator to choose to collect or not a sample as evidence. A positive result indicates a strong likelihood for the presence of human blood. A lab analysis will later confirm or infirm this presumption.

HEXAGON OBTI is a two-part test : a collection tube for the blood sample, and a test bar. A sample of the presumed human blood trace is transferred into the tube with transport medium. This mixture is added drop by drop to the test. A positive sample is typically detected within 2-5 minutes. A single red line means the testing liquid is working fine but no human blood has been detected, two red/pink lines mean the test has detected human blood.

Principle
Human hemoglobin (hHb) in the sample reacts with a reagent consisting of red colored particles and monoclonal anti-human Hb antibodies. The immunocomplex migrates to the test zone where it is captured by an immobilized second antibody directed against hHb forming a pink test line to indicate a positive result. Unreacted reagents migrate further and are bound in a second line by immobilized anti-mouse lgC antibodies. This red control line indicates proper function and correct handling of the test. The test detects whole blood up to a dilution of 1 : 2,000,000. As little as 250 red cells are required for a positive result. The new improved HEXAGON OBTI, easier to read thanks to its red lines is now capable of detecting 0.05 ľg/ml hemoglobin and has a storage temperature up to 30°C.

False positives
Positive results were obtained with blood from primates (gorilla, and of some Mustelidae (weasel, badger). The blood of the following animals did not react with the Hexagon OBTI : cattle, pig, sheep, goat, horse, rabbit, chicken, duck, goose, turkey, guinea pig, red deer, cat, dog. A positive result is not in itself an evidence of the presence of human blood but it indicates a high probability of its presence.