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The Kastle–Meyer test is a presumptive blood test, first described in 1903, in which the chemical indicator phenolphthalein is used to detect the possible presence of hemoglobin. It relies on the peroxidase -like activity of hemoglobin in blood to catalyze the oxidation of phenolphthalin (the colorless reduced form of phenolphthalein) into ...
If the sample contains hemoglobin, it will turn pink immediately upon addition of the peroxide, because of the generation of phenolphthalein. A positive test indicates the sample contains hemoglobin and, therefore, is likely blood. A false positive can result from the presence of substances with catalytic activity similar to hemoglobin.
As with all presumptive tests, this technique can produce false positive results due to metals and strong chemicals, such as bleach, that will also react. Another common presumptive test is the Kastle-Meyer or Phenolphthalein test. This is a catalytic test that detects the heme group in blood that transports oxygen and carbon dioxide. [5]
Most people who take a drug test take a presumptive test, cheaper and faster than other methods of testing. However, it is less accurate and can render false results. The FDA recommends for confirmatory testing to be conducted and the placing of a warning label on the presumptive drug test: "This assay provides only a preliminary result.
Lastly, a droplet of mixture of monomers (e.g., PEGDA and N-vinyl pyrrolidone) and phenolphthalein is added to the test strip, and the droplet is illuminated with green visible light, by which the eosin molecules become excited and produce radicals. (Figure 1c) As a result, propagation is caused and polymers are formed. [citation needed]
2. Excessive Stress. Stress is a natural, normal part of the human experience, and your body knows how to handle it. When you’re under stress, your body releases stress hormones that activate ...
Phenol red was used by Leonard Rowntree and John Geraghty in the phenolsulfonphthalein test to estimate the overall blood flow through the kidney in 1911. [9] It was the first test of kidney function and was used for almost a century but is now obsolete. The test is based on the fact that phenol red is excreted almost entirely in the urine.
They also “kept denying” her and her husband Charles’ requests for an electroencephalogram (EEG) test, which measures electrical activity in the brain, when they noticed Caper’s feet ...