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Bials Test

Qualitative Test of Carbohydrate Bials Test Bial’s test is a chemical test performed to detect the presence of pentoses and pentosans (derivatives of pentoses). A derivation of this test termed the Bial’s Orchintest is performed to detect the presence of RNA in solutions. This test is based on the principle that under hydrolysis pentosans are hydrolyzed into pentoses. Further, pentoses are dehydrated to yield furfural, which in turn condense with orcinol to form a blue-green precipitate. In the presence of hexoses, hydroxyfurfural is formed instead of furfural which upon condensation with orcinol forms a muddy brown colored precipitate. The intensity of the precipitation is directly proportional to the concentration of the pentoses in the sample. The intensity of the color developed depends on the concentration of HCl, ferric chloride, orcinol, and the duration of boiling.