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- Posts: 3
- Joined: Fri May 22, 2020 9:49 am
Just to give a little background, we do a QuEChERS extraction and then inject the samples on LC/MS and GC/MS. Our calibration range is 5-500 ppb, with standards spiked in a matrix matched solution. We incorporate QC’s where we spike and extract negative matrix exactly the same way we extract the samples.
Problems:
1. How do we calculate the concentration in the 10g sample from the concentration read from the instrument (in the vial)? Is there some sort of dilution and conversion factors that one has to consider when calculating? That after the QuEChERS extraction.
2. We spike the QC with 300ppb analyte and then extract exactly like our samples. Then the instrument will read the QC at approximately 300ppb. Does that mean there is no dilution in the whole extraction? (QuEChERS)
Summary of extraction:
10g sample + 10ml Acetonitrile > 1ml aliquot in dSPE > Dry the 1ml aliquot and make up in 200ul > Inject 2ul of the 200ul extract.
Please help...