Titration

Q1: What is titration?

A: Titration is a laboratory technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration (called the titrant).

Q2: What is Titrant?

• Definition: The titrant is the solution of a known concentration used in a titration. It is gradually added to the analyte (titrate) to determine its concentration.
• Purpose: It reacts with the titrate in a stoichiometric manner to reach the equivalence point.

Example:
In an acid-base titration, if you’re determining the concentration of HCl, NaOH (sodium hydroxide) would act as the titrant.

• Titrant: Known concentration; added using a burette.

Q3: What is Titrate (or Analyte)

• Definition: The titrate is the solution of unknown concentration (or the substance to be analyzed) in a titration.
• Purpose: It reacts with the titrant, and its concentration is calculated based on the reaction at the endpoint.

Example:
If you’re analyzing the concentration of an acetic acid solution, the acetic acid is the titrate.

• Titrate: Unknown concentration; usually in a flask.

Q4: What are the main types of titration used in pharmaceuticals?

A: Common types include:

1. Acid-base titration: Determines the concentration of acidic or basic substances.
2. Redox titration: Involves an oxidation-reduction reaction (e.g., potassium permanganate titration).
3. Complexometric titration: Used for metal ion analysis (e.g., EDTA titration).
4. Non-aqueous titration: Determines the concentration of weak acids or bases in non-water solvents.

Q5: What is an indicator, and why is it used in titration?

A: An indicator is a chemical substance that changes color at a specific pH or reaction endpoint, helping to visually identify when the titration reaction is complete.

Q6: What quantity of indicator to be added during titration as per general notices in Pharmacopeia?

A: Approximately 0.2 mL, or 3 drops, of the solution shall be added unless otherwise specified.

Q7: What is the endpoint in titration?

A: The endpoint is the point at which the reaction between the titrant and the analyte is complete, usually indicated by a color change.

Q8: What is the difference between endpoint and equivalence point?

A:

• Equivalence point: The exact point where the amount of titrant is stoichiometrically equal to the amount of analyte.
• Endpoint: The observable point where the indicator changes color, which should ideally match the equivalence point.

Q9: What is the role of titration in pharmaceuticals?

A: Titration is used for:

1. Assaying active pharmaceutical ingredients (APIs).
2. Determining the purity of raw materials.
3. Standardizing solutions for quality control.

Q10: What are common titrants used in pharmaceutical titrations?

A:

1. Sodium hydroxide (NaOH): For acid-base titration.
2. Hydrochloric acid (HCl): For basic substances.
3. Potassium permanganate (KMnO4): For redox titration.
4. Ethylenediaminetetraacetic acid (EDTA): For complexometric titration.

Q11: What is non-aqueous titration, and why is it important?

A: Non-aqueous titration is a method performed in solvents other than water, often used for titrating weak acids or bases that do not dissolve well in water. It is critical in pharmaceuticals for analyzing drugs like amines and carboxylic acids.

Q12: What are the key steps in a titration procedure?

A:

1. Prepare the sample and titrant.
2. Add a suitable indicator to the sample.
3. Slowly add the titrant to the sample while stirring.
4. Observe the color change and record the volume of titrant used at the endpoint.
5. Calculate the concentration of the unknown solution.

Q13: What are common errors in titration, and how can they be minimized?

A:
Errors:

1. Misjudging the endpoint (indicator overshot).
2. Impurities in the sample or titrant.
3. Incorrect calibration of equipment.

Minimization:

1. Use a suitable indicator with a sharp color change.
2. Perform the titration slowly near the endpoint.
3. Calibrate the burette and pipette before use.

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