Which of the following is NOT a step in MALDI-TOF mass spectrometry steps?

• A. PCR amplification
• B. Ionization of molecules
• C. Measured mass-to-charge ratio
• D. Generation of a molecular signature

Answer: (A)

MALDI-TOF mass spectrometry identifies samples by their protein fingerprint. In practice, a small amount of the specimen is mixed with a chemical matrix and crystallized. A laser then ionizes the molecules (desorption/ionization), and these ions are sped through a time-of-flight tube. The time it takes for each ion to reach the detector depends on its mass-to-charge ratio, producing a spectrum that serves as a molecular signature used to identify the organism or compound by comparing it to a reference database. This workflow relies on ionization, measuring mass-to-charge ratios, and generating a spectral fingerprint.

PCR amplification is not part of MALDI-TOF steps. PCR is a DNA amplification technique used to increase nucleic acid material for other methods, such as sequencing or nucleic acid–based tests. MALDI-TOF analyzes proteins directly and does not involve amplifying DNA, which is why amplification does not belong in its sequence.