If the tracer concentration of a 1:2,000 dilution is 0.05 uCi/mL, what is the tracer concentration of the original solution?

To determine the tracer concentration of the original solution from the given dilution, it’s essential to understand the concept of dilution and how it affects concentration.

In a 1:2,000 dilution, the original solution is diluted to a total of 2,000 parts, meaning that 1 part of the original solution is mixed with 1,999 parts of a solvent (commonly water). This dilution means that the concentration of the tracer in the diluted solution is only a fraction of the original concentration.

Since the tracer concentration of the diluted solution is given as 0.05 uCi/mL, the original concentration can be calculated by multiplying the diluted concentration by the dilution factor. The dilution factor in this case is 2,000, so you would compute:

Original concentration = Diluted concentration × Dilution factor

Original concentration = 0.05 uCi/mL × 2,000 = 100 uCi/mL

This calculation indicates that the original solution had a tracer concentration of 100 uCi/mL, which aligns with the correct answer choice. Understanding how to apply dilution factors to find the original concentration is critical in nuclear medicine for preparing and measuring doses accurately.