What is the role of internal standards in mass spectrometry-based assays?

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Multiple Choice

What is the role of internal standards in mass spectrometry-based assays?

Internal standards are added to each sample in a known, fixed amount to normalize the entire analytical process. They experience the same extraction losses, chromatography, and ionization fluctuations as the target analyte, so comparing the analyte signal to the internal standard signal corrects for variability from sample prep to detector response. Using an isotopically labeled analog as the standard is ideal because it mirrors the analyte’s chemical behavior and extraction efficiency but can be distinguished by mass, allowing accurate quantification without interference. This approach improves precision and accuracy across samples and accounts for matrix effects that can suppress or enhance signal. They’re not used to adjust pH, they’re not only for external calibration, and they do more than provide qualitative ID—their primary role is enabling reliable quantification by compensating for process variability.

Internal standards are added to each sample in a known, fixed amount to normalize the entire analytical process. They experience the same extraction losses, chromatography, and ionization fluctuations as the target analyte, so comparing the analyte signal to the internal standard signal corrects for variability from sample prep to detector response. Using an isotopically labeled analog as the standard is ideal because it mirrors the analyte’s chemical behavior and extraction efficiency but can be distinguished by mass, allowing accurate quantification without interference. This approach improves precision and accuracy across samples and accounts for matrix effects that can suppress or enhance signal.

They’re not used to adjust pH, they’re not only for external calibration, and they do more than provide qualitative ID—their primary role is enabling reliable quantification by compensating for process variability.

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