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PART II - MAJOR EXPERIMENT
Q. 2a: Limit Test for Chlorides (35 Marks)
Name: [Your Name]
Roll No.: [Your Roll No.]
Date: 27-05-2026
LIMIT TEST FOR CHLORIDES
Aim
To perform the limit test for chlorides in the given sample and report whether it complies with the standard.
Principle
The limit test for chlorides is based on the reaction between chloride ions (Cl⁻) present in the sample and silver nitrate (AgNO₃) in the presence of dilute nitric acid (HNO₃). This reaction produces a white turbidity or precipitate of silver chloride (AgCl), which is compared with a standard turbidity prepared from a known amount of chloride (NaCl).
Reaction:
NaCl + AgNO₃ → AgCl↓ (white turbidity) + NaNO₃
The turbidity produced by the sample should not be more than that produced by the standard solution.
Requirements
| S.No. | Apparatus / Reagents | Specification |
|---|---|---|
| 1. | Nessler cylinders (matched pair) | 50 mL, flat-bottomed |
| 2. | Silver nitrate solution | 2% w/v in water |
| 3. | Dilute nitric acid | As per IP |
| 4. | Standard chloride solution | 5 ppm (prepared from NaCl) |
| 5. | Sample solution | As directed |
| 6. | Distilled water | - |
Preparation of Standard Chloride Solution (Stock)
- Dissolve 0.824 g of Sodium Chloride (NaCl, previously dried at 110°C) in distilled water and make up to 1000 mL (Stock Solution = 500 ppm Cl⁻).
- Dilute 10 mL of this to 1000 mL → Standard Chloride Solution = 5 ppm (1 mL = 5 μg Cl⁻).
Procedure
Step 1 - Preparation of Test Solution (Nessler Cylinder A):
- Take the prescribed amount of sample in a Nessler cylinder.
- Add distilled water to make 40 mL.
- Add 10 mL of dilute nitric acid (HNO₃).
- Mix well.
Step 2 - Preparation of Standard Solution (Nessler Cylinder B):
- Pipette the volume of standard chloride solution as specified (e.g., 1 mL = 5 μg Cl⁻).
- Add distilled water to make 40 mL.
- Add 10 mL of dilute nitric acid (HNO₃).
- Mix well.
Step 3 - Development of Turbidity:
- To both cylinders, add 1 mL of 2% silver nitrate solution.
- Add 0.1 mL of dilute nitric acid.
- Make up to 50 mL with distilled water in both cylinders.
- Mix and allow to stand for 5 minutes, protected from light.
Step 4 - Comparison:
- View the cylinders longitudinally against a black background, in diffused light.
- Compare the turbidity of the test solution with that of the standard.
Observation Table
| Observation | Test Solution (A) | Standard Solution (B) |
|---|---|---|
| Appearance | White turbidity / opalescence | White turbidity (reference) |
| Comparison | Less / Equal / More than standard | Reference |
Result
The opalescence produced by the Test Solution (A) is not more than / more than that produced by the Standard Solution (B).
The sample COMPLIES / DOES NOT COMPLY with the IP limit test for Chlorides.
(Fill based on actual observation)
Limit (as per IP)
The limit of chlorides in the sample is not more than [X] ppm as specified in the Indian Pharmacopoeia.
Precautions
- Nessler cylinders used must be matched (identical diameter and flat bottom).
- The test must be carried out under identical conditions for both cylinders simultaneously.
- Protect from direct light after adding AgNO₃ (AgCl is photosensitive).
- Use dilute HNO₃ only (not dilute HCl or H₂SO₄ - they interfere).
- Distilled water used must be chloride-free.
- Both cylinders should be viewed from the top against a black background.
PART II - MINOR EXPERIMENT
Q. 2b - BATCH A: Identification of Unknown Drug Sample (Paracetamol / Ibuprofen)
Aim
To identify the given unknown drug sample as Paracetamol or Ibuprofen by performing suitable qualitative chemical tests.
Principle
Paracetamol (Acetaminophen) and Ibuprofen can be distinguished by their specific chemical reactions based on their functional groups:
- Paracetamol contains a phenolic -OH group and an amide (-NHCOCH₃) group
- Ibuprofen contains a carboxylic acid (-COOH) group and an isobutyl group
Tests Performed
TEST 1 - Ferric Chloride Test (for Phenolic group)
| Step | Procedure |
|---|---|
| Reagent | Aqueous FeCl₃ solution |
| Take | Small amount of sample dissolved in water/ethanol |
| Add | 2-3 drops of 1% FeCl₃ solution |
Observation:
| Drug | Result |
|---|---|
| Paracetamol | Blue-violet / purple colour appears |
| Ibuprofen | No colour change (negative) |
TEST 2 - Hydrolysis followed by Diazo Coupling Test
| Step | Procedure |
|---|---|
| Boil | Sample with dilute HCl for 5 minutes (hydrolysis) |
| Cool | To room temperature |
| Add | Sodium nitrite (NaNO₂) solution at 0-5°C |
| Add | β-Naphthol solution in NaOH |
Observation:
| Drug | Result |
|---|---|
| Paracetamol | Orange-red / cherry-red diazo dye (azo coupling - free primary amine formed after hydrolysis) |
| Ibuprofen | No diazo coupling (no primary amine) |
TEST 3 - Sodium Bicarbonate (Effervescence) Test (for -COOH group)
| Step | Procedure |
|---|---|
| Take | Small amount of sample |
| Add | Sodium bicarbonate (NaHCO₃) solution |
Observation:
| Drug | Result |
|---|---|
| Paracetamol | No effervescence |
| Ibuprofen | Brisk effervescence (CO₂ evolved - acidic -COOH present) |
TEST 4 - Melting Point (Physical Test)
| Drug | Melting Point |
|---|---|
| Paracetamol | 168-172°C |
| Ibuprofen | 75-77°C |
Observation Summary Table
| Test | Paracetamol | Ibuprofen | Given Sample |
|---|---|---|---|
| FeCl₃ test | Blue-violet colour | No colour | _______ |
| Diazo coupling | Orange-red colour | No colour | _______ |
| NaHCO₃ test | No effervescence | Effervescence | _______ |
| Melting point | 168-172°C | 75-77°C | _______ |
Result
The given unknown drug sample is identified as _______________ (Paracetamol / Ibuprofen) based on the positive results of the above qualitative tests.
Q. 2b - BATCH B: Assay of Aspirin by Acid-Base Titration Method
Aim
To determine the percentage purity of Aspirin (Acetylsalicylic acid) by acid-base back titration method.
Principle
Aspirin (Acetylsalicylic acid) is hydrolysed by excess sodium hydroxide (NaOH) on boiling. The excess NaOH is then back-titrated against standard sulphuric acid (H₂SO₄) using phenolphthalein as indicator.
Reactions:
Step 1 - Hydrolysis (Saponification):
C₉H₈O₄ + 2 NaOH → C₇H₅O₃Na (Sodium Salicylate) + CH₃COONa + H₂O
Step 2 - Back Titration:
2 NaOH + H₂SO₄ → Na₂SO₄ + 2 H₂O
Molecular weight of Aspirin = 180.16 g/mol
1 mL of 0.5 M H₂SO₄ ≡ 1 mL of 1 M NaOH ≡ 0.09008 g of Aspirin
Requirements
| S.No. | Material | Specification |
|---|---|---|
| 1. | Aspirin sample | ~0.5 g, accurately weighed |
| 2. | NaOH solution | 0.5 M, standardised |
| 3. | H₂SO₄ solution | 0.25 M (0.5 N), standardised |
| 4. | Phenolphthalein indicator | 1% in alcohol |
| 5. | Conical flask | 250 mL |
| 6. | Burette, Pipette | Standard |
| 7. | Water bath / hot plate | - |
Procedure
Step 1:
- Weigh accurately about 0.5 g of Aspirin sample. Record weight as W g.
Step 2:
- Transfer to a 250 mL conical flask.
- Add exactly 50 mL of 0.5 M NaOH using a pipette.
Step 3:
- Boil gently on water bath for 15 minutes (to complete hydrolysis of ester bond).
- Cool to room temperature.
Step 4 - Back Titration:
- Add 2-3 drops of phenolphthalein indicator (pink colour appears).
- Titrate excess NaOH with 0.25 M H₂SO₄ from the burette.
- End point: Pink colour just disappears (colourless).
- Note the volume of H₂SO₄ consumed = V mL.
Calculation
Let:
- Volume of NaOH taken = 50 mL of 0.5 M
- Volume of H₂SO₄ used in back titration = V mL of 0.25 M
Milliequivalents of NaOH taken:
= 50 × 0.5 = 25 mmol
Milliequivalents of NaOH consumed by H₂SO₄ (excess):
= V × 0.25 × 2 = 0.5V mmol
Milliequivalents of NaOH consumed by Aspirin:
= 25 - 0.5V mmol
Since 1 mmol NaOH ≡ 0.5 mmol Aspirin (2 moles NaOH per mole Aspirin):
Moles of Aspirin = (25 - 0.5V) / 2 mmol
Weight of Aspirin = Moles × Mol. wt.
= [(25 - 0.5V) / 2] × 0.18016 g
% Purity:
$$% \text{ Purity} = \frac{\text{Weight of pure Aspirin found}}{\text{Weight of sample taken (W)}} \times 100$$
Observation Table
| S.No. | Initial burette reading (mL) | Final burette reading (mL) | Volume of H₂SO₄ used (V mL) |
|---|---|---|---|
| 1. | |||
| 2. | |||
| 3. | |||
| Concordant reading |
Result
The percentage purity of the given Aspirin sample = ________ %
(IP limit: Aspirin should contain not less than 99.5% of C₉H₈O₄, calculated on dried basis)
The sample COMPLIES / DOES NOT COMPLY with IP standards.
Precautions
- Boiling must be complete to ensure total hydrolysis of Aspirin.
- Cool the solution completely before back-titration.
- All glassware must be clean and dry.
- Standardise both NaOH and H₂SO₄ before use.
- Take concordant readings (within 0.1 mL).
- End point should be sharp - faint pink to colourless.
Q. 2b - BATCH C: Storage Conditions and Uses of Atropine Sulphate and Propranolol
ATROPINE SULPHATE
Chemical Name: (1R,3r,5S)-8-Methyl-8-azabicyclo[3.2.1]octan-3-yl 3-hydroxy-2-phenylpropanoate sulphate
Chemical Formula: (C₁₇H₂₃NO₃)₂.H₂SO₄
Molecular Weight: 676.8 g/mol
Category
Anticholinergic (Muscarinic antagonist) drug
Mechanism of Action
Atropine competitively antagonises the muscarinic receptors of acetylcholine. It blocks the effects of parasympathetic nervous system (vagolytic action), causing:
- Increased heart rate (tachycardia)
- Decreased secretions (dry mouth, reduced sweating)
- Mydriasis (pupil dilation)
- Relaxation of smooth muscles
Uses of Atropine Sulphate
- Pre-anaesthetic medication - to reduce secretions during surgery
- Antidote for organophosphate poisoning (blocks excessive acetylcholine effects)
- Treatment of bradycardia (slow heart rate)
- Ophthalmology - pupil dilation (mydriatic) for eye examination and uveitis
- Antispasmodic - in peptic ulcer, renal colic, intestinal colic
- Asthma - as bronchodilator (older use)
- Motion sickness (scopolamine related use)
Storage Conditions of Atropine Sulphate
- Store in a well-closed container, protected from light
- Store in a cool, dry place (below 25°C)
- Protect from moisture (hygroscopic in nature)
- Schedule H drug - store separately, under lock and key
- Keep away from children
- Avoid exposure to heat and direct sunlight
- Aqueous solutions should be freshly prepared and sterilised by autoclaving
PROPRANOLOL
Chemical Name: (RS)-1-(Isopropylamino)-3-(naphthalen-1-yloxy)propan-2-ol hydrochloride
Chemical Formula: C₁₆H₂₁NO₂.HCl
Molecular Weight: 295.8 g/mol
Category
Non-selective Beta-adrenergic blocker (Beta-blocker)
Mechanism of Action
Propranolol competitively blocks both β₁ (heart) and β₂ (lungs, blood vessels) adrenergic receptors. This results in:
- Decreased heart rate (negative chronotropy)
- Decreased force of contraction (negative inotropy)
- Decreased cardiac output
- Reduction in blood pressure
Uses of Propranolol
- Hypertension - reduces blood pressure
- Angina pectoris - reduces cardiac oxygen demand
- Cardiac arrhythmias - controls atrial fibrillation, SVT, ventricular arrhythmias
- Myocardial infarction - reduces mortality post-MI
- Hyperthyroidism - controls tachycardia and tremor (thyrotoxicosis)
- Migraine prophylaxis
- Anxiety and tremors (stage fright, essential tremor)
- Phaeochromocytoma (with alpha-blockers)
- Portal hypertension - reduces risk of bleeding from oesophageal varices
Storage Conditions of Propranolol
- Store in a well-closed, light-resistant container
- Store below 25°C in a cool, dry place
- Protect from moisture and heat
- Schedule H drug - prescription only, kept under lock and key
- Keep away from children
- Do not store in bathroom (humid conditions degrade the drug)
- Tablets should be stored at controlled room temperature (15-30°C)
Comparison Table
| Feature | Atropine Sulphate | Propranolol |
|---|---|---|
| Drug class | Anticholinergic | Beta-blocker |
| Receptor | Muscarinic (M) | β₁ and β₂ adrenergic |
| Effect on HR | Increases | Decreases |
| Key use | Organophosphate poisoning, bradycardia | Hypertension, arrhythmia |
| Storage | Cool, dark, dry; Schedule H | Cool, dark, dry; Schedule H |
| Light sensitivity | Yes | Yes |
All answers written above are formatted as per standard D.Pharm practical examination format including aim, principle, procedure, observation table, calculation (where applicable), result, and precautions.
Give answers of synopsis in 2 marks only no extra
PART I - SYNOPSIS (10 Marks)
Q. 1a) What are sulfonamides? Give two examples. (2 Marks)
Sulfonamides are synthetic antimicrobial drugs containing the sulfonamide group (-SO₂NH₂). They act by inhibiting bacterial folic acid synthesis by competitively antagonising PABA.
Examples:
- Sulfamethoxazole
- Sulfadiazine
Q. 1b) Define cathartics with two examples. (2 Marks)
Cathartics are drugs that promote rapid evacuation of bowel contents by increasing intestinal motility or softening the stool.
Examples:
- Castor oil
- Magnesium sulphate (Epsom salt)
Q. 1c) What are dental products? Give examples. (2 Marks)
Dental products are pharmaceutical preparations used for oral hygiene, prevention and treatment of dental diseases like caries, gingivitis and infections.
Examples:
- Sodium fluoride (toothpaste/mouthwash)
- Zinc chloride (antiseptic mouthwash)
Q. 1d) Example of antihypertensive drug. (2 Marks)
Antihypertensive drugs are agents used to lower elevated blood pressure (hypertension).
Examples:
- Amlodipine
- Enalapril
Q. 1e) What are beta-blockers? Give two examples. (2 Marks)
Beta-blockers are drugs that competitively block β-adrenergic receptors, reducing heart rate, cardiac output and blood pressure.
Examples:
- Propranolol
- Atenolol
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