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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5986_Библиотеки_им_академика_М_И_Перельмана.pdf
157
Qualitative Analysis of Inorganic and Organic Drugs
4. On exposure to moist air, the crystals rapidly oxidize and become brown
5. Readily soluble in boiling water; freely soluble in water; practically
insoluble in ethanol
Chemical test: Ferrous sulphate gives reactions for the ferrous salt and
sulphate salts.
Chemical test
S. no. Experiment Observation Inference
1. Ferrous ion
To 1 mL of a solution of ferrous
sulphate, add potassium ferricyanide
solution (1 mL).
Add sodium hydroxide solution.
To 1 mL of a solution containing not
less than 1 mg of ferrous sulphate,
add potassium ferrocyanide solution
(1 mL).
Add dilute hydrochloric acid.
A dark blue precipitate is
formed.
Precipitate dissolves.
A white precipitate is
formed which rapidly
becomes blue.
Precipitate is insoluble.
Indicates the formation
of ferriferricyanide.
Formation of potassium
ferroferrocyanide.
2. Sulphate
To the solution of ferrous sulphate
(1 gm in 20 mL) (5 mL) add dilute
hydrochloric acid (1 mL) and barium
chloride solution (1 mL).
Add lead acetate solution (2 mL) to
ferrous sulphate solution (5 mL).
White precipitate or
turbidity appears.
A white precipitate appears.
Indicates the formation
of barium sulphate.
Lead sulphate is formed.
Reaction involved
S. No. 1
With potassium ferricyanide
Fe K Fe CN
Ferrous ion
Potassium
Ferricyanide
++ +
++
()
⎡
⎣
⎢
⎤
⎦
⎥
⎯→⎯2
6
4-
⎯⎯⎯⎯
()
⎡
⎣
⎢
⎤
⎦
⎥
KFe Fe CN
2
6
With potassium ferrocyanide
2FeSO + K Fe CN
4
Ferrous
sulphate
4
6
Potassium ferrocyanide
()
⎡
⎣
⎢
⎤
⎦
⎥
⎯⎯→⎯⎯⎯
()
⎡
⎣
⎢
⎤
⎦
⎥
(
Fe F CN
2
6
Ferrous ferrocyanide
White precipitate
e
))
+
[]
↓
⎯→⎯⎯⎯⎯
()
⎡
⎣
⎢
⎤
⎦
⎥
+2KSO
Fe Fe CN
24
O,Air
4
6
3
Prussian blue
158
Practical Pharmaceutical Analytical Chemistry
S. No. 2
With barium chloride
SO BaCl BaSO
Sulphate ion
Barium chloride
Barium sulpha
42 4
+⎯→⎯⎯⎯ ↓
tte
White precipitate
()
With lead acetate
SO CH COO Pb PbSO
Sulphate ion
Lead acetate
Lead sulph
43
2
4
+
()
⎯→⎯⎯⎯ ↓
aate
white precipitate
()
Experiment 8 To perform identification tests with a given sample of
hydrogen peroxide
H
2
O
2
Molecular weight: 34
Pharmaceutical Use: Antiseptic and deodorant; topical anti-infective
Procedure
Physical test
1. Clear, colourless liquid
2. Odourless
3. Slightly acidic in taste
4. It decomposes vigorously in contact with oxidisable organic matter and
with certain metals and also if allowed to become alkaline
5. Available in two concentrations, i.e. strong hydrogen peroxide
solution (27%; 100Vol) and dilute hydrogen peroxide solution
(6%; 20Vol)
Chemical test
S. no. Experiment Observation Inference
1. Add dilute sodium hydroxide solution
(1 mL) to hydrogen peroxide and heat it.
Effervescence is produced. Indicates the
formation of oxygen.
2. To 1 mL of hydrogen peroxide solution,
add 2 mL of dilute sulphuric acid and
shake the mixture. Then, add one drop of
potassium chromate solution and 2 mL of
solvent ether.
Blue colour appears in
ethereal layer.
Indicates the
formation of
chromium
pentaoxide.
159
Qualitative Analysis of Inorganic and Organic Drugs
Reaction involved
S. No. 1
With sodium hydroxide
22
22 2 2
HO HO O
Hydrogen peroxide Water Oxygen
⎯→⎯⎯⎯ + ↑
S. No. 2
With potassium chromade and sulphuric acid
KCrO HSO HO
Potassium
Chromate
Sulphuric
acid
Hydrogen
pe
24 24 22
2++
rroxide
Chromium
pentaoxide
Potassium
sulphate
CrO K SO⎯→⎯⎯⎯ + +
524
33
2
HO
Water
Result The given sample was identified as hydrogen peroxide.
Experiment 9 To perform identification tests with a given sample of
magnesium sulphate (Epsom salt)
MgSO
4
·7H
2
O
Molecular weight: 246.47
Pharmaceutical Use: Osmotic laxative, used in the treatment of electrolyte
deficiency
Procedure
Physical test
1. Colourless crystals or white crystalline powder
2. Odourless
3. Taste of the salt is cool, saline, and bitter
4. Effloresces in warm dry air
5. Highly soluble in boiling water, freely soluble in water, practically
insoluble in ethanol (95%)
160
Practical Pharmaceutical Analytical Chemistry
Chemical test:
Magnesium sulphate gives reaction of magnesium and
sulphate ion
Reaction involved
S. No. 1
With ammonia solution
Mg NH OH Mg OH NH
Magnesium ion
Ammonium hydroxide
M
++
+⎯→⎯⎯⎯
()
+22
4
2
4
aagnesium
hydroxide
With disodium hydrogen phosphate
Mg NH HPO Mg NH PO
Magnesium ion
Hydrogen
phosphate
M
++
++ ⎯→⎯⎯⎯
()
34
4
4
aagnesium ammonium
phosphate
S. No. 2
With barium chloride
SO BaCl BaSO Cl
Sulphate ion
Barium chloride
Barium s
42 4
2
+⎯→⎯⎯⎯ ↓ +
uulphate
White precipitate
()
Chemical test
S. no. Experiment Observation Inference
1. Magnesium ion
To magnesium sulphate solution
(2 mL) add dilute ammonia
solution (1 mL)
Add 1 mL of 2 M ammonium
chloride.
Further, add disodium hydrogen
phosphate (1 mL; 0.25 M).
White precipitate is
obtained.
The precipitate gets
dissolved.
A white crystalline
precipitate is formed.
Indicates the formation of
magnesium hydroxide.
Due to the formation of
magnesium ammonium
phosphate.
2. Sulphate
To the solution of ferrous sulphate
(1 gm in 20 mL) (5 mL) add dilute
hydrochloric acid (1 mL) and
barium chloride solution (1 mL).
Add lead acetate solution (2 mL)
to ferrous sulphate solution (5 mL)
White precipitate or
turbidity appears.
A white precipitate
appears.
Indicates the formation of
barium sulphate.
Lead sulphate is formed.
161
Qualitative Analysis of Inorganic and Organic Drugs
With lead acetate
SO CH COO Pb PbSO
Sulphate ion
Lead acetate
43
2
4
+
()
⎯→⎯⎯⎯ + 2CHCOO
3
LLead sulphate
White precipitate
()
RESULT The given sample was identified as magnesium sulphate.
Experiment 10 To perform identification tests with a given sample of
potassium permanganate
KMnO
4
Molecular weight: 158.03
Pharmaceutical Use: Antiseptic
Procedure
Physical test
1. Dark purple or brownish black, granular powder or dark purple or
almost black slender, prismatic crystals
2. Has metallic lustre
3. Odourless
4. It decomposes on contact with certain organic substances
5. Taste is sweet and astringent
6. Soluble in cold water; freely soluble in boiling wate
r
Chemical test
S. no. Experiment Observation Inference
1. Heat potassium permanganate to
redness in a dry test tube.
Decrepitation (black
residue) is observed.
Evolution of oxygen and
potassium manganate
(black residue).
162
Practical Pharmaceutical Analytical Chemistry
2. Dissolve the black residue in water
and neutralize the solution with
dilute hydrochloric acid. To 1 mL of
the solution, add dilute acetic acid
(1 mL) and sodium cobaltinitrite
(1 mL; 10% w/v).
Add sodium carbonate solution
(1 mL) and heat.
Further, add sodium sulphide
solution.
Cool in ice and add tartaric acid
(2 mL; 15% w/v).
Yellow or orange yellow
precipitate is observed.
No precipitation occurs.
No precipitation occurs.
White crystalline
precipitate is formed.
Indicates the formation of
potassium cobalti nitrite.
Potassium hydrogen
tartarate is formed.
3. Ignite a small amount of potassium
permanganate and dissolve in
minimum quantity of water. To
the solution, add 1 mL of platonic
chloride followed by 1 mL of
hydrochloric acid.
A yellow crystalline
precipitate is formed.
Potassium
hexachloroplatinite is
formed.
4. Acidify the potassium permanganate
solution with sulphuric acid. Heat
to about 70qC and add hydrogen
peroxide solution.
Pink colour is discharged. Due to the formation
of colourless manganese
ions.
Reaction involved
S. No. 1
2
424
KMnO K MnO
Potassium
permanganate
Heat
Potassium
mangan
⎯→⎯⎯⎯⎯
aate
Mangnese
oxide
Oxygen
MnO O++↑
22
S. No. 2
With sodium cobaltinitrite
K
+
Potassium ion Sodium cobaltinitrite
Na
3
[Co(NO
2
)
6
]
K
3
[Co(NO
2
)
6
]
Potassium cobaltinitrite
yellow precipitate
With tartaric acid
K
+
Potassium ion Potassium hydrogen tartarate
CH(OH)COOK
CH(OH)COOH
CH(OH)COOH
CH(OH)COOH
Tartaric acid
163
Qualitative Analysis of Inorganic and Organic Drugs
S. No. 3
2
6
KPtCl
Potassium ion
Hexachloraplatinic acid
or platinic
+
+
[]
cchloride
Potassium hexachloroplatinite
Yello
KPtCl⎯→⎯⎯⎯
[]
↓
26
(ww crystalline precipitate)
S. No. 4
25
422
KMnO H O
Potassium
permagnate
Pink colour
Hydrogen
peroxid
()
+
ee
Sulphuric acid
Magnesium
sulphate
Colourl
HSO
MnSO
+
⎯→⎯⎯⎯
3
2
24
4
(eess
Potassium
sulphate
Oxygen
Water
KSO O HO
)
++↑+
24 2 2
5
Result The given sample was identified as potassium permagnate.
Experiment 11 To perform identification tests with a given sample of
sodium bicarbonate
NaHCO
3
Molecular weight: 84.01
Pharmaceutical Use: Electrolyte replenisher; systemic alkalizer
Procedure
Physical test
1. White, crystalline powder or small, opaque, monoclinic crystals
2. Odourless
3. Free
ly soluble in water; practically insoluble in ethanol (95%)
Chemical test: Sodium bicarbonate gives reactions for sodium ions and
bicarbonate ions
Chemical test
S. no. Experiment Observation Inference
1. Sodium ion
To the solution, add potassium
antimonate solution and boil the
mixture.
Add magnesium uranyl acetate
solution (a solution of uranyl
acetate and magnesium acetate in
dilute acetic acid).
White precipitate is
observed.
Yellow crystalline
precipitate is formed.
Sodium antimonite is
formed.
Due to the formation of
sodium magnesium uranyl
acetate.
164
Practical Pharmaceutical Analytical Chemistry
2.
Carbonate ion
Boil the solution.
Add acetic acid solution.
Pass this gas into barium hydroxide
solution.
Add dilute hydrochloric acid.
Add magnesium sulphate to the
solution and boil the mixture.
Effervescence occurs.
Effervescence occurs.
White precipitate is
obtained.
Precipitate gets dissolved.
A white precipitate is
formed.
Due to the evolution of
carbon dioxide.
Due to the evolution of
carbon dioxide.
Indicative of formation of
barium carbonate.
Due to formation of
soluble barium chloride.
Indicates the formation of
magnesium carbonate.
Reaction involved
S. No. 1
With potassium animonate
Na KSbO NaSbO
Sodium ion
Potassium antimonate Sodium ant
+
+⎯→⎯⎯⎯ ↓
33
iimonate
White precipitate()
+K
+
With magnesium uranyl acetate
Na Mg UO CH COO
Sodium ion
Magnesium ion
Acetate ion
+++ −− −
+++
⎯→⎯
39
23
⎯⎯⎯
()( )
↓NaMg UO CH COO
Sodium magnesium
uranyl acetate
Yellow
2
3
3
9
(ccrystalline
precipitate)
S. No. 2
On boiling
2
3232
NaHCO Na CO CO
Sodium bicarbanate Sodium carbanate
Carb
⎯→⎯⎯⎯ +
oon dioxide
Effervescene
Water
HO
()
+
2
S. No. 2
With acetic acid
NaHCO CH COOH CH COONa
Sodium
bicarbanate
Acetic
acid
Sodi
33 3
+⎯→⎯⎯⎯
uum
acetate
Carbon
dioxide
Water
Barium hydroxide
CO H O
Ba OH
++
()
22
2
++⎯→⎯⎯⎯ ↓ +CO BaCO H O
Carbon dioxide
Barium carbonate
Water
232
165
Qualitative Analysis of Inorganic and Organic Drugs
BaCO HCl
Barium carbanate
White precipitate
Hydrochloric
ac
3
2↓+
()
iid
Carbon
di
BaCl CO⎯→⎯⎯⎯ ↓ +
22
Barium chloride
soluble precipitate ooxide
Water
HO+
2
With magnesium sulphate
2
34 24
NaHCO MgSO Na SO
Sodium
bicarbanate
Magnesium
sulphate
+⎯→⎯⎯⎯
SSodium
sulphate
Magnesium
carbanate
White precipitate
MgCO+↓
3
())
++CO H O
Carbon
dioxide
Water
22
Result The given sample was identified as sodium bicarbonate.
166
Practical Pharmaceutical Analytical Chemistry
Judge yourself
1. Write the structure of the following:
(i) Ascorbic acid
(ii) Aspirin
(iii) Calcium gluconate
2. How will you identify boric acid based on chemical tests?
3. Differentiate between magnesium and ferrous sulphate based
on their chemical tests.
4. Sodium bicarbonate gives yellow crystalline precipitate with
magnesium uranyl acetate solution. What does this indicate?
5. Effervescence is observed on boiling sodium bicarbonate
solution. What does this indicate?
6. What will happen if sulphuric acid is added to potassium
permanganate solution and the mixture further heated to
about 70
q
C followed by addition of hydrogen peroxide
solution?
7. Write the reaction for identification of magnesium ions
using qualitative tests.
8. Write the solubility behaviour of following:
(i) Boric acid
(ii) Barium sulphate
(iii) Ascorbic acid.