1. Starch
Reagent Used: Iodine solution
Positive Result: Blue-black color
Negative Result: Brown/amber color
Tip: Think of the color change like an ink blot turning dark (starch is present).
2. Monosaccharides (Simple Sugars)
Reagent Used: Fehling’s or Benedict’s solution
Positive Result: Orange/red precipitate
Negative Result: Blue color
Tip: Remember “sugar burns to red.”
3. Disaccharides
Reagent Used: Fehling’s or Benedict’s solution
Positive Result: Orange/red precipitate
Negative Result: Blue color
4. Proteins
Reagent Used: Biuret reagent
Positive Result: Purple to pink color
Negative Result: Blue color
5. Fats and Oils
Reagent Used: Ethanol
Positive Result: Milky or translucent suspension
Negative Result: No emulsion or translucent spot
6. Vitamin C
Reagent Used: DCPIP (Dichlorophenolindophenol)
Positive Result: Blue to colorless
Negative Result: Blue color
Tip: Vitamin C “clears the blue.”
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Reagent Used: Iodine solution
Positive Result: Blue-black color
Negative Result: Brown/amber color
Tip: Think of the color change like an ink blot turning dark (starch is present).
2. Monosaccharides (Simple Sugars)
Reagent Used: Fehling’s or Benedict’s solution
Positive Result: Orange/red precipitate
Negative Result: Blue color
Tip: Remember “sugar burns to red.”
3. Disaccharides
Reagent Used: Fehling’s or Benedict’s solution
Positive Result: Orange/red precipitate
Negative Result: Blue color
4. Proteins
Reagent Used: Biuret reagent
Positive Result: Purple to pink color
Negative Result: Blue color
5. Fats and Oils
Reagent Used: Ethanol
Positive Result: Milky or translucent suspension
Negative Result: No emulsion or translucent spot
6. Vitamin C
Reagent Used: DCPIP (Dichlorophenolindophenol)
Positive Result: Blue to colorless
Negative Result: Blue color
Tip: Vitamin C “clears the blue.”
Share 👍