pH Measurement Process with Glass Electrode

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What is the purpose of maintaining the freezing point depression of the drug solution at -0.52°C?

To prevent the drug solution from becoming hypertonic.

To increase the viscosity of the drug solution.

To enhance the taste of the drug solution.

To ensure the drug solution remains isotonic. (correct)

What is the key factor that needs to be adjusted to make the drug solution isotonic?

Type of adjusting substance

Freezing point depression of the solution

Volume of the drug solution

Concentration of the drug (correct)

How is the required percentage weight/volume (w/v) of an adjusting substance calculated?

(0.52 + d) / a

(0.52 - d) / a (correct)

(d - 0.52) / a

(0.52 - d) * a

What happens to the freezing point depression if the AT value of the adjusting substance (a) increases?

The freezing point depression increases. Signup and view all the answers

If the % w/v of an adjusting substance needed is calculated to be 5%, what could be a possible value for 'd' in this scenario?

-0.2 Signup and view all the answers

In equation (1), what does 'Total drug solution AT' represent?

The freezing point depression of the complete drug solution Signup and view all the answers

What is the advantage of using a glass electrode for pH measurement?

High accuracy in pH measurement Signup and view all the answers

Why is the cost of a pH meter considered a disadvantage over the colorimetric method?

The pH meter is more expensive Signup and view all the answers

What role do pH indicators play in determining the pH of a test solution?

Producing a color change to indicate pH Signup and view all the answers

Why are glass electrodes not affected by the oxidation-reduction system?

They establish equilibrium rapidly Signup and view all the answers

What characteristic makes a universal indicator different from other indicators?

It gives different color shades at different pH levels Signup and view all the answers

Why is the method using a glass electrode not suitable for viscous solutions and gels?

Viscous solutions hinder proper equilibrium establishment Signup and view all the answers

What is the pH range for Methyl yellow indicator?

3.1-4.4 Signup and view all the answers

When does the colour change occur for Methyl red indicator?

Red-yellow Signup and view all the answers

What is the pH range for Thymol blue indicator?

8.0-9.6 Signup and view all the answers

What is the main purpose of adjusting the pH of pharmaceutical formulations?

Enhancing solubility Signup and view all the answers

What does buffer capacity refer to?

The amount of acid/base required to produce a unit change in pH Signup and view all the answers

Why is it important to add a buffer of desired pH to enzyme preparations?

To optimize biological activity Signup and view all the answers

What is the range of buffer capacity generally considered adequate for pharmaceutical buffers?

0.05 to 0.5 Signup and view all the answers

Which buffer system cannot be used to stabilize a solution for oral or parenteral administration due to its toxic effects?

Borate buffer Signup and view all the answers

What is the pH range of blood that poses a danger to life according to the text?

7.0 to 7.8 Signup and view all the answers

Which primary buffer system is present in plasma according to the text?

Carbonic acid-bicarbonate system Signup and view all the answers

What is the total buffer capacity for whole blood as indicated in the text?

0.0315 Signup and view all the answers

What are the two secondary buffer systems present in erythrocytes according to the text?

Haemoglobin/oxyhemoglobin system and acid/alkali salts of phosphoric acid system Signup and view all the answers

What is the purpose of the White Vincent method in the context of ophthalmic solutions?

To make an isotonic solution by adding drugs and diluting vehicles Signup and view all the answers

In the context of Class II methods, what does the sodium chloride equivalent refer to?

The weight of the drug multiplied by the equivalent amount of sodium chloride Signup and view all the answers

What is the significance of the ratio 100/0.9 in the White Vincent method?

It represents the volume of isotonic solution that can be prepared Signup and view all the answers

What does the term 'tonicity' refer to in relation to ophthalmic solutions?

The osmotic pressure of the solution Signup and view all the answers

How does the White Vincent method simplify the process of preparing ophthalmic solutions?

By adjusting both the tonicity and pH simultaneously Signup and view all the answers

What quantity does 0.063g of sodium chloride represent in terms of procaine hydrochloride weight equivalence?

$0.063W$ Signup and view all the answers