What does positive benzidine test mean?

What does positive benzidine test mean?

: a sensitive test for the presence of blood (as in urine or feces) based on the production of a blue color upon contact with a solution of benzidine, hydrogen peroxide, and glacial acetic acid.

What color is a positive benzidine test?

Positive ( + ): a deep blue colour, appearing within 15 seconds. Weakly positive (±): a greenish-blue colour, appearing within 30 seconds.

Is benzidine specific for blood?

Early workers found benzidine to be a sensitive and specific test for blood. In time benzidine was discovered to be nonspecific for blood but specific for peroxidase.

How do you perform a benzidine test?

The method recommended in most textbooks for making the benzidine test consists in adding to 1 cc. of a saturated acetic acid solution of benzidine, 1 cc. of t,he suspected liquid, and 1 cc. of 3 per cent hydrogen dioxide.

Why is TMB light sensitive?

TMB is light sensitive and is therefore packaged in amber bottles to protect the solution from direct sunlight. The reaction between the TMB substrate and a peroxidase, typically horseradish peroxidase (HRP), produces a measur- able color change that correlates with analyte level.

Is benzidine test reliable to test the presence of blood?

Early workers found benzidine to be a sensitive and specific test for blood. In time benzidine was discovered to be nonspecific for blood but specific for peroxidase. Because of its lack of specificity, man workers have discouraged its use [3- 5].

How do you prepare a benzidine solution for a blood test?

What happens if TMB is exposed to light?

TMB should be kept out of direct sunlight as it is photosensitive. It is not known if TMB is carcinogenic and the evidence is contradictory: TMB is not mutagenic by the Ames test, and did not induce formation of tumors in a single-arm study of 24 rats.

What is a benzidine test used for?

Benzidine test: Benzidine test is a specific test used for the determination of blood (RBCs or haemoglobin) in urine. Kidney diseases or any injury to the urinary tract may result in leakage of blood in the urine.

How do you reduce benzidine solution?

H2O2 reduce benzidine solution. In this solution, the iron of haemoglobin gives blue colour complex. Benzidine reagent: 1. Benzidine dihydrochloride 2. Glacial acetic acid 3% hydrogen peroxide. Take 3 ml of fresh benzidine reagent in a test tube. Add 2 ml of urine in it. And also add 1 ml of 3% hydrogen peroxide in it.

Does benzidine darken on exposure to air and light?

It darkens on exposure to air and light. Benzidine is a diamine, manufactured as synthetic aromatic hydrocarbon with two benzene rings covalently bonded to one another (1,1), substituted by amino group at 4,4′.

What is the difference between benzidine and guaiac test?

The guaiac test is, however, less sensitive than the benzidine test and up to 20 cc. of blood may be ingested without producing a positive test (30). For this reason the test is suitable only as a rather crude screening test. Other Therapeutic Agents Hepler (18) has stated that iodides and bromides give positive reactions.

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