Practical No.1 Flashcards
Molisch’s Test
a general test for the presence of carbs
How does the Molisch Test work?
concentrated sulfuric acid hydrolyzes glycosidic bonds to give the monosaccharides which are then dehydrated to furfural and its derivatives
What is the result of a ‘successful’ Molisch Test?
purple-violet color
Benedict’s Test
a test that can be used to check for the presence of reducing sugars using glucose and sucrose
How does the Benedict test work?
The aldehyde or ketone group of the carbs reduces blue cupric hydroxide to an insoluble coloured cuprous oxide
What happens if no carb is present in the Benedict’s’ Test?
the cupric hydroxide (when heated) is converted to an insoluble black cupric oxide
What is the result of a Benedict’s Test?
it gives a blue color
Seliwanof’s Test
this test detects for ketoses using fructose
How does the Seliwanof’s test work?
Ketoses are dehydrated more rapidly than aldoses to give furfural derivatives, which condenses with resorcinol (part of reagent) to form a pink complex
What is the result to a Seliwanof’s Test?
a pink color
Iodine ides
they test for starch
How do iodine ides work?
iodine forms colored absorption complexes with polysaccharides like starch gives a blue color with iodine, while glycogen and partially hydrolyzed starch give red-brown colors
