1. What is Sub-Stoichiometric Isotope Dilution Analysis?

Definition: SSIA is an analytical technique used to determine the quantity of a substance in an unknown solution by using a radioactive tracer and measuring specific activities.

Purpose: It's particularly useful for trace analysis when dealing with very small quantities of substances in complex matrices.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( m_2 \) — Amount of compound in unknown solution (kg)
• \( m_1 \) — Amount of compound in stock solution (kg)
• \( S_1 \) — Specific activity of stock solution (Bq/kg)
• \( S_2 \) — Specific activity of mixed solution (Bq/kg)

Explanation: The formula calculates the unknown quantity by comparing the specific activities before and after mixing with a known radioactive tracer.

3. Importance of SSIA

Details: This method provides high sensitivity and accuracy for measuring trace elements, especially in environmental, biological, and geological samples.

4. Using the Calculator

Tips: Enter the known values of the stock solution (amount and specific activity) and the measured specific activity of the mixed solution. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What units should I use for input?
A: Use kilograms (kg) for mass and becquerels per kilogram (Bq/kg) for specific activity.

Q2: Why is this called "sub-stoichiometric"?
A: Because the method uses less than the stoichiometric amount of reagent needed for complete reaction with the analyte.

Q3: What are typical values for specific activity?
A: These vary widely depending on the radionuclide used, but often range from thousands to millions of Bq/kg.

Q4: How accurate is this method?
A: SSIA can achieve accuracy within 1-2% when performed carefully with proper calibration.

Q5: What are common applications?
A: Environmental monitoring, pharmaceutical analysis, forensic science, and biochemical research.