PAG09 = Qualitative Testing Flashcards
What test do we use to test for proteins?
Biuret test
What is the method of the biuret test?
- Add sodium
hydroxide solution. - Add copper (II)
sulphate solution
What is a positive result for the biuret test?
Colour change from blue
to purple.
What test do we use to test for starch?
iodine test
What is the method of the iodine test?
- Add iodine in
potassium iodide
solution.
What is a positive result for the iodine test?
Colour change from
brown-orange to
blue-black.
What test do we use to test for lipids?
emulsion test
What is the method of the emulsion test?
- Add ethanol.
- Pour solution into
water
What is a positive result for the emulsion test?
Solution goes a milky / cloudy
colour.
What test do we use to test for reducing sugars?
Benedict’s Test
What is the method of the reducing sugars benedict’s test?
- Add Benedict’s
reagent to a sample and
heart in a water bath
that’s brought to a boil.
What is a positive result for the reducing sugars benedict’s test?
sample goes from blue (to green to yellow to orange) to brick red precipitate, depending on the concentration.
What test do we use to test for non reducing sugars?
Benedicts test
What is the method of the non reducing sugars benedict’s test?
- Add dilute HCl.
- Put in a water bath
brought to a boil. - Neutralise with
sodium hydrogen
carbonate. - Do Benedict’s Test
for reducing sugars.
What is a positive result for the non reducing sugars benedict’s test?
Sample goes from blue (to green to yellow to orange) to brick red precipitate, depending on the concentration.
What test do we use to test for glucose?
reagent test strips
What is the method of the glucose test?
- Dip test strip in
solution.
What is a positive result for the glucose test?
Colour change will occur if glucose is present. Compare to chart of known colour changes to check for concentration.
