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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Highlander81 on February 22, 2011, 07:40:16 AM

Title: Calculation of recovery from a matrix spike QC sample
Post by: Highlander81 on February 22, 2011, 07:40:16 AM

Pyrene in soil samples was extracted by sonic extraction followed by analysis using HPLC. A stock solution of pyrene (50 l, 100 mg/L) in acetonitrile was spiked (added) in a clean soil (0.5 g) and was extracted with 10 ml hexane. A portion of the extract (10 l) was injected to HPLC and the concentration of the extract was determined to be 0.45 mg/L. Calculate the percentage recovery of the extraction.

Anyone able to help me with this?

Title: Re: Calculation of recovery from a matrix spike QC sample
Post by: JGK on February 22, 2011, 03:08:22 PM

The problem does not make sense, Did you really spike a 0.5 g sample with 50 l of a 100 mg/mL solution?

Check the text and correct please

Title: Re: Calculation of recovery from a matrix spike QC sample
Post by: Highlander81 on February 25, 2011, 03:31:03 AM

Sorry, it is supose to be:

Pyrene in soil samples was extracted by sonic extraction followed by analysis using HPLC. A stock solution of pyrene (50 µl, 100 mg/L) in acetonitrile was spiked (added) in a clean soil (0.5 g) and was extracted with 10 ml hexane. A portion of the extract (10 µl) was injected to HPLC and the concentration of the extract was determined to be 0.45 mg/L. Calculate the percentage recovery of the extraction.

Title: Re: Calculation of recovery from a matrix spike QC sample
Post by: JGK on February 25, 2011, 02:17:17 PM

Quote from: Highlander81 on February 25, 2011, 03:31:03 AM

Sorry, it is supose to be:

Pyrene in soil samples was extracted by sonic extraction followed by analysis using HPLC. A stock solution of pyrene (50 µl, 100 mg/L) in acetonitrile was spiked (added) in a clean soil (0.5 g) and was extracted with 10 ml hexane. A portion of the extract (10 µl) was injected to HPLC and the concentration of the extract was determined to be 0.45 mg/L. Calculate the percentage recovery of the extraction.

Calculate the No. of milligrams Pyrene spiked in to the soil sample.

If all (100%) of this sample was extracted in 10 mL, what would the concentration be in mg/ml?

Convert that value to mg/L

What percentage of the above mg/L value is the actual value of 0.45 mg/mL?