Internal Standard
Advantage
An internal standard is used to correct losses during sample preparation and to correct matrix effects during the mass spectrometric analysis. In general the internal standard should be chemically similar to the analyte, but should not naturally occur in the samples. The optimal internal standard is the isotopically labeled standard.
Disadvantage
If no isotopically labeled standard is available, a similar compound should be used. Nevertheless differences in extraction or ionization efficiency might occur.
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