PAGS Flashcards
1) what’s the test for sugars?
2) what’s the test for non reducing sugars?
3) what the test for starch?
4) whats the test for proteins?
5) what’s the test for lipids?
1) benedict’s test
2) benedict’s test
3) iodine test
4) buiret test
5) emulsion test
how would you carry out the test for reducing sugars?
benedict’s test:
1) place sample to be tested in a boiling tube, if it’s not liquid grind or blend it
2) add equal volume of benedict’s reagent
3) heat mixture gently in boiling bath for 5min
what happens if reducing sugars are present?
participate
🟦 🟩 🟨 🟧 🟥 blue->red
brick red precipitate is formed=positive
concentration of reducing sugar- the more red and more precipitate
how do you test for non reducing sugars?
benedict’s test:
1) break down into monosaccharides
2) dilute hydrochloride acid, heat it in a boiling water bath, then neutralise with sodium hydrogencarbonate then add benedict’s reagent.
what happens if non reducing sugars are present?
positive:
🟦🟩🟨🟧🟥 blue -> red
forms red brick precipitate
what’s a reducing sugar?
whats a non reducing sugar?
• reducing: all monosaccharides, some disaccharides
• non reducing: sucrose most common
how do you test for starch?
iodine test:
1) add few drops of iodine dissolved in potassium iodide solution to test sample
what happens if starch is present?
browny orange -> blue black
how do you carry out test for proteins?
biuret test:
1) test solution needs to be alkaline, so add a few drops of sodium hydroxide solution.
2) add cooper(ll) sufate solution
what happens if protein is present?
🟦>🟪
how do you test for lipids?
1) shake test substance with ethanol for 1min, then pour into water
how do you test for lipids?
emulsion test:
1) shake test substance with ethanol for 1min, then pour into water
what happens if lipids are present?
turn milky, more lipid=more milky
how can you determine concentration of chemical substance?
benedict’s reagent + colorimeter = quantitive determine concentration in a solution
