Question

Recovery standards are a necessary tool for determining exactly how much of a particular analyte you are able to extract from a sample. You have a recovery standard that contains 4.0 mg Fe/1.0000 g sample, d.w. Your analysis determines that you extracted 3.5 mg Fe from 1.0101 g sample. A sample that you ran in parallel with the recovery standard returned a measurement of 1.7 mg Fe in 0.9582 g sample. How much iron (mg Fe/g sample) is actually present in your sample?

Answer 1

Answer:

2.05mg Fe/ g sample

Explanation:

In all chemical extractions you lose analyte. Recovery standards are a way to know how many analyte you lose.

In the problem you recover 3.5mg Fe / 1.0101g sample: 3.465mg Fe / g sample. As real concentration of the standard is 4.0 mg / g of sample the percent of recovery extraction is:

3.465 / 4×100 = 86,6%

As the recovery of your sample was 1.7mg Fe / 0.9582g, the Iron present in your sample is:

1.7mg Fe / 0.9582g sample× (100/86.6) = 2.05mg Fe / g sample

I hope it helps!