Question

Which one of the following is a correct combination of ionizer and analyser that can make a Mass Spectrometer useful to analyze biomolecules?

• A. Quadrupole(Q)-Time-of-flight (TOF)
• B. Matrix-assisted laser desorption ionization (MALDI)-Time-of-flight (TOF)
• C. Time-of-flight (TOF)
• D. Quadrupole-ion trap

Hint:

For large biomolecules, think "soft ionization." The two main soft ionization techniques are \textbf{MALDI} and Electrospray Ionization (ESI). MALDI is commonly paired with a \textbf{TOF} analyzer.

Answer 1

The Correct Option is B

Step 1: Problem definition. Mass spectrometry of large, delicate biomolecules (proteins, DNA) needs "soft" ionization to avoid destruction and an analyzer that handles high mass-to-charge (m/z) ratios.

Step 2: Solution assessment.
(1) Quadrupole(Q)-Time-of-flight (TOF): This is a hybrid analyzer (Q-TOF), not an ionizer-analyzer pair.
(2) MALDI-TOF: This is a proven, effective combination. MALDI is a soft ionization technique where the biomolecule is mixed with a matrix, which absorbs laser energy and gently charges the analyte. TOF is a mass analyzer that separates ions by flight time, and it has a high mass range, ideal for large biomolecules.
(3) & (4) These options only list analyzers, not the required ionizer-analyzer combination.
Conclusion: MALDI-TOF is the best choice for biomolecule analysis.