Benzidine-based tests (e.g., Hematest) have been virtually eliminated from use because of their excessive sensitivity, which results in a high frequency of false-positive reactions, as well as the carcinogenicity of the reagent.

Experimental evidence has been presented showing that a daily ingestion of at least 5 c.c. of blood divided in three equal doses with meals is necessary to give a positive test for occult blood in the stools when the benzidine reagent is used. When tolidin reagent is used from 2 to 4.5 c.c. of blood could be detected.

If a blue or green color appears within 30 seconds, the test is said to be positive for occult blood irrespective of diet. The sensitivity of this reagent was tested against known dilutions of blood and was found to give a negative reaction with dilutions greater than 1 in 40,000.

In 1964, Culliford and Nickolls [1] published an in-depth review of the benzidine test. They found that false positives could be obtained from blood contamination, chemical oxidants, catalysts, and vegetable peroxidases.

of glacial acetic acid in a clean test-tube, thus obtaining a 0-5 per cent, solution of benzidine hydrochloride. Then either the examining finger of a rectal glove or a clean orange-stick dipped in a faecal specimen is smeared on white filter-paper, and a little of the benzidine solution is poured over the smear.

benzidine, an organic chemical belonging to the class of amines and used in making numerous dyestuffs. This process is the simplest case of a general reaction, the benzidine rearrangement. Benzidine, a colourless, crystalline solid, practically insoluble in water, is toxic, causing dermatitis and bladder tumours.

For the occult blood tests, 39 (14.1%) patients were positive for both tests, while 198 (71.5%) were negative by both tests….Table 4.

Fasting prior to sample collection For the Gut Microbiome (GI) test, you do not need to fast before collecting your stool sample. You can collect your sample at any time of the day.

A false positive test would occur when the test was positive but you do not have any signs of polyps or cancer. This happens approximately 25% of the time. This can be the result of other issues (such as inflammation or hemorrhoids) causing blood to be present in the stool.

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.

Ingestion of benzidine causes cyanosis, headache, mental confusion, nausea and vomiting. Its use is now limited because of strong association between exposure to benzidine and an increased risk of bladder cancer in humans.

Benzidine is prepared from nitrobenzene in a two-step process: nitrobenzene is converted to 1,2-diphenylhydrazine, usually using iron powder as the reducing agent, and then hydrazine is treated with mineral acids to induce a rearrangement reaction to 4,4′-benzidine.

Benzidine is a manufactured chemical that does not occur naturally. It is a crystalline solid that may be grayish-yellow, white, or reddish-gray. In the environment, benzidine is found in either its “free” state (as an organic base), or as a salt. Benzidine was used to produce dyes for cloth, paper, and leather.