1. What is a Sink Condition Calculator?

Definition: This calculator determines the sink condition in dissolution processes by comparing solubility to actual concentration.

Purpose: It helps pharmaceutical scientists and chemical engineers assess whether sink conditions are maintained in dissolution testing.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \text{Sink} \) — Sink condition (dimensionless)
• \( C_s \) — Solubility of the compound (mg/L)
• \( C \) — Actual concentration in solution (mg/L)

Explanation: Sink conditions exist when the ratio is significantly greater than 1 (typically >3), meaning concentration is much less than solubility.

3. Importance of Sink Condition

Details: Maintaining sink conditions ensures proper dissolution testing by preventing saturation effects that could alter dissolution rates.

4. Using the Calculator

Tips: Enter the compound's solubility and the actual concentration in solution (both in mg/L). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What defines sink conditions?
A: Sink conditions are generally considered to exist when Cₛ/C > 3, meaning the concentration is less than one-third of the solubility.

Q2: Why are sink conditions important?
A: They ensure dissolution rates aren't affected by concentration gradients and maintain consistent driving force for dissolution.

Q3: What affects solubility (Cₛ)?
A: Temperature, pH, solvent composition, and polymorphic form can all significantly impact a compound's solubility.

Q4: How do I measure concentration (C)?
A: Typically measured using UV spectroscopy, HPLC, or other analytical techniques during dissolution testing.

Q5: What if my ratio is close to 1?
A: A ratio near 1 indicates potential saturation, which may require increasing media volume or changing conditions to maintain sink.