The peroxidase-like activity of Haemoglobin catalises the reaction of hydrogen peroxide and o-Dianisidine to form a BLUE colour in acid medium indicating the presence of free Haemoglobin.
|Cat. No. AR 605
Contains bovine haemoglobin -0.1%, preservatives
Preparation of Working Reagent
All Reagents are ready to use.
Stable at 25-35°C for 2 years.
Hydrogen peroxide may deteroriate on exposure to
light. In such condition use commercially available 6%
Sample can be urine, bodyfluids or faeces. As food contains large amount of vegetable peroxidase (from vegetables) and myoglobin (from meat diet), it makes false positive reaction in stool samples. Therefore, boil the stool sample at 100°C for one minute and instruct patient not to take nonvegetarian foods for atleast 18 hours prior to stool collection. (All samples should be handled as potential infective agents as no laboratory methods make conclusive findings for its safety. Therefore, adequate protective laboratory measures should be taken while handling such materials).
This test is highly sensitive to peroxidase like activity of free haemoglobin. False negative may be observed in case of occassional unruptured RBC. Low concentration of Hydrogen peroxide makes false negative results. Strong H202 (30%) bleach the final colour leading to false negative.
False positive result may be observed in stool samples containing vegetable peroxidase and myoglobin from food intake. Contamination of peroxidase enzyme from reagent like God-Pod make false positive results. avoid using commercially available filter paper as it may contain vegetable peroxidase, leading to false positive results.
Sprinkle a pinch of HAEMTEST™ Powder and a drop of Activator (6% Hydrogen Peroxide) to the sample on a piece of filter paper. Formation of immediate blue colour indicates presence of occult blood. Run a Negative and Positive control to establish the accuracy of methodology.
If the sample under test shows
1.Immediate dense blue colour - Strong Positive
2.Light blue colour - Positive
3.Weak blue colour - Trace
4.No blue colour - Negative
Positive and Negative controls show confirmatory results respectively.
1.Harrison, GA, (1947) Chemical methods in Clinical medicine, 3rd Ed Churchill London.
2.King E.J. and Kelly, T, (1955) J. Clin. Path 8,249
3.Moss, D.G. (1955) J. Med.Lab. Tech. 13.22