SCHEME FOR THE IDENTIFICATION OF

UNKOWN SUBSTANCESPhysical propertiesChemical properties

Presented byDr Nada Soliman

name…………number……...

Number of the unknown Physical properties:1. Shape2. Color3. Odor4. Taste5. Solubility6. Reaction7. Heat dry test

Chemical properties

test observation result

unknown possibilities:

CHO proteinReducing non reducing heat-coagulable non heat-coag

Glucose starch sucrose albumin and peptone gelatinMaltose globulineLactose(consideredAs onesolution)

3 solutions 3 solutions

Physical Properties

1. ShapeA. Powder e.g. starch.B. Crystals e.g. sugars.

2. Color.3. Odor.4. Taste: The unknown substance

may be:A. Sweet e.g. sugarsB. Tasteless e.g. starch

5. Solubility:A. Cold water: e.g. sugars urea,….etc.B. Hot water: e.g. starch and gelatin

6. Reaction7. Heat dry test: Heat a small portion of

the unknown substance in a dry test tube

A. Odor of burnt bread e.g. starch.B. Odor of caramel e.g. sugars.C. Odor of burnt haire.g. Protein

Chemical Properties

We have 3 solutions of protein, one of them : egg white solution (source of albumine and globuline)is a natural solution which contain beside protein, CHO

So we start the scheme with biuret test (test specific for protein)

Biuret test Heat coagulationtest

Millon’s test

test Observation Result

1. Biuret test2. Heat coagulation

test

3. Salting out

4. Millon’s test

Violet color White ppt in the

upper part of the test tube

ppt with ½ saturated (NH4)2SO4 solution

ppt with fully saturated (NH4)2SO4 solution

Brick red ppt

Protein solution heat coagulable

protein (albumin & globulin)

Globulin

Albumin

Protein contain

Tyrosine

Biuret test Heat coagulationtest

Millon’s test

test Observation result

1. Biuret test2. Heat Coagulation

test

3. Millon’s test

4. Sulfur test

Violet color No white ppt in the

upper part of the test tube

Brick red ppt

Black ppt

Protein solution non-heat

coagulable protein (peptone or gelatin)

Protein containing tyrosine: peptone

Proteine containing sulfur containing aa (cystine et cysteine): peptone

Biuret test Heat coagulation test

Millon’s test

Test Observation Result

1. Biuret test 2. Heat coagulation

test

3. Millon’s test

4. Sulfur test

Violet color No white ppt in the

upper part of the test tube

No brick red ppt

No Black ppt

Protein solution non-heat

coagulable protein (peptone or gelatin)

Protein doesn’t contain tyrosine: gelatin

Protein doesn’t contain cystine or cysteine: gelatin

biuret test

violet color no violet color (protein) (not protein)

heat coagulation test

whit ppt no white ppt (heat- coagulable (non- heat coagulable protein: albumin) protein: peptone or & globulin ) gelatin)

millon’s test millon’ s test

brick red ppt brick red ppt no brick red ppt (tyrosine) (protein contain (doesn’t contain tyrosine: tyrosine: peptone) gelatin) sulfur test sulfur test

black ppt no black ppt (protein contain (doesn’t contain sulfur aa: peptone sulfur aa :gelatin)

Biuret test molisch test Iodine test

test observation result

1. Biuret test2. Molisch test3. Iodine test4. Fehling after

hydrolysis

No violet color Reddish violet ring Deep blue Color Red ppt

Not protein CHO solution starch Products of

hydrolysis of starch have free anomeric carbon atoms

Biuret test Molisch test Iodine test Fehling test

Essai Observation Resultat

1. Biuret test2. Molisch test3. Iodine test4. Fehling test

5. Osazone test

No violet color Reddish violet ring No Deep blue Color Red ppt

Needle- shaped crystals

Plate- shaped crystals

Rosette- shaped crystals

Not protein CHO solution Not starch Reducing sugar

( glucose, maltose ou lactose)

Glucose

Maltose

lactose

Biuret test Molisch test Iodine test Fehling test Seliwanoff test

Essai Observation Result

1. Biuret test2. Molisch test3. Iodine test4. Fehling test

5. Seliwanoff test

6. Fehling after hydrolysis

No violet color Reddish violet ring No Deep blue Color No Red ppt

Red onion peel color

Red ppt

Not protein CHO solution Not starch Non Reducing

sugar (sucrose) Sucrose

Products of hydrolysis of sucrose have free anomeric carbon atoms

molisch test reddish violet ring no reddish violet ring (CHO) (not CHO)

iodine test

Deep blue color no deep blue color (starch) (not starch)

Fehling after Fehling test hydrolysis red ppt no red ppt (reducing sugar) (non-reducing)

osazone test seliwanoff test

crystals red onion peel color ( sucrose) fehling after hydrolysis