Formula Used:
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Definition: DIDA is an analytical technique used to determine the quantity of an unknown substance by adding a known amount of a radioisotope of the same element and measuring the change in specific activity.
Purpose: It's widely used in chemistry, biochemistry, and environmental science for precise quantification of substances in complex mixtures.
The calculator uses the formula:
Where:
Explanation: The formula calculates the unknown quantity by comparing the dilution of radioactivity when mixed with the unknown substance.
Details: DIDA provides highly accurate measurements even in complex matrices where other analytical methods might fail, and doesn't require complete separation of the analyte.
Tips: Enter the mass of labelled compound added (y), initial specific activity (Si), and final specific activity after mixing (Sf). All values must be > 0 and Si > Sf.
Q1: What units should I use for the inputs?
A: Mass should be in kilograms (kg) and specific activity in becquerels per kilogram (Bq/kg).
Q2: Why must Si be greater than Sf?
A: This indicates dilution occurred. If they're equal, no unknown substance was present to dilute the radioactivity.
Q3: What if I get a negative result?
A: Check your inputs - this usually means Sf was greater than Si, which isn't physically possible in this context.
Q4: How precise should my measurements be?
A: For best results, use as precise measurements as possible, especially for specific activities.
Q5: Can I use different units?
A: Yes, but all units must be consistent (e.g., all in grams and Bq/g).