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BCH 2720 IBM

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BCH 2720 IBM Expt.1: Qualitative Tests for Carbohydrates and Amino Acids 1a: Carbohydrates Characterization Molisch s Test : carbohydrate Barfoed s Test ... – PowerPoint PPT presentation

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Title: BCH 2720 IBM


1
BCH 2720 IBM
  • Expt.1
  • Qualitative Tests for Carbohydrates and Amino
    Acids

2
1a Carbohydrates Characterization
  • Molischs Test carbohydrate
  • Barfoeds Test Monosaccharides and
    Oligosaccharides
  • Seliwanoff Test Differentiation of Ketose from
    Aldose
  • Iodine Test Cellulose, Starch, Dextrin

3
Experiment 1 Qualitative Tests for Carbohydrates
I. Principle
1. Molischs Test - test for carbohydrates
a-naphthol
conc.H2SO4
Pentose/ Hexose
Furfural
5-hydroxymethyl furfural (Purple complex)
- H2O
2. Barfoeds Test - test for reducing sugars
- test for distinguishing monosaccharides and
disaccharides
Slightly acidic
Reducing sugar 2Cu2
2Cu oxidized sugar
Cu2O (brick red ppt)
3. Seliwanoff Test - test for distinguishing
ketose from aldose
resorcinol
conc. HCl
5-hydromethyl furfural
Ketohexose
red complex
dehydration
4. Iodine Test - test for starch
Starch I2
starch - I2 complex (deep blue)
4
Barfoed's Test
RCHO    2Cu2    2H2O -----gt   RCOOH    Cu2O 
  4H Barfoed's reagent reacts with
monosaccharides to produce cuprous oxide at a
faster rate than disaccharides do
5
Monosaccharide Disaccharides 
  • Monosaccharide
  • Glucose
  • Fructose
  • Disaccharides 
  • Maltose
  • Lactose
  • Sucrose

6
Ketone Adehyde
7
Polysaccharide
  • Starch
  • Glycogen
  • Cellulose

8
Molischs Test
  • Test for carbohydrate materials
  • Using 2 ml of test solution in a test tube, add
    50 ?l of the ? 1-naphthol, mix and then allow 1
    ml of conc. Sulphuric acid to flow down the side
    of the inclined tube to layer under the mixture.
    Note the colour at the junction.

9
Barfoeds Test
  • Test for Monosaccharides and Oligosaccharides
  • Using 0.5 ml of test solution, mix with 2.5 ml of
    Barfoeds solution in a test tube and boil for 15
    minutes. Note the time of first sign of
    precipitate appears. After 15 minutes, cool it
    down and observe the amount of precipitate in
    each tube.

10
Seliwanoff Test
  • Test for Differentiation of Ketose from Aldose
  • Add 0.5 ml of the test solution to 2.5 ml of the
    Seliwanoffs reagent. Place the tubes in boiling
    water and note the results and continue heating,
    observe the colour change at 1 minute interval
    for 5 minutes.

11
Iodine Test
  • Test for Cellulose, Starch, Dextrin
  • Add 50 ?l of aqueous iodine solution to 4 ml test
    solution. Record the colours observed. Then heat
    the tubes 5 mins, record the effect on the
    colours, cool the tube again and note the effect
    on the colours.

12
1b. General Properties of amino acids
  • The Ninhydrin Reaction oxidising agent
  • (It reacts with ?-amino acids to produce a
    purple coloured compound to measure the amount of
    ?-amino acid in a sample.)

13
The Ninhydrin Reaction
  • Mix 1 ml of test solution and 50 ?l of ninhydrin
    reagent in a test tube. Boil for 5 minutes and
    observe the colour change. (Tyrosine, Tryptophan
    Proline)
  • serial dilution of glycine

14
(No Transcript)
15
Ruhemanns Pruple
16
Lab Report
  • Control is Water
  • Date of Experiment 24 Jan 2006 (Tue)
  • Date of Submission 10 Feb 2006 (Before 500p.m.)
    (Fri)
  • Demonstrator in-charge Edmond
  • Room no. MMW 612A

17
Lab Report (Cont)
  • Title and Introduction - 0.5 M
  • Results 2.5 M
  • Discussion 5 M
  • Conclusion and Recommendation 1.5 M
  • Reference 0.5 M
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