What is a key advantage of mass spectrometry over immunoassays in clinical testing?

• A. Mass spectrometry offers high analytical specificity and can quantify multiple analytes with less interference and cross-reactivity.
• B. Mass spectrometry is always cheaper than immunoassays.
• C. Mass spectrometry cannot quantify more than one analyte at a time.
• D. Mass spectrometry relies on antibody binding.

Answer: (A)

Mass spectrometry offers superior analytical specificity and multiplexing capability in clinical testing. By measuring the exact mass-to-charge ratio and fragmentation patterns of ions, MS distinguishes compounds with similar structures far more reliably than antibody-based methods, minimizing interference from related molecules and matrix effects. This high specificity means accurate quantification even in complex samples. Additionally, MS can monitor many distinct analytes in a single run, enabling multiplex testing, which is much harder to achieve with immunoassays due to cross-reactivity and limited antibody availability. Immunoassays rely on antibody binding and can suffer from cross-reactivity and interference, whereas mass spectrometry detects the analyte itself by its physical properties, not by an antibody, though it may require more specialized equipment.