Question

In mass spectrometry, Resolution power $R$ (the ability to differentiate between two masses) is best represented as: (where $m$ = nominal mass at which peak occurs and $\Delta m$ = mass difference between two resolved peaks)

• A. $R = \Delta m$
• B. $R = \Delta m / m$
• C. $R = m / \Delta m$
• D. $R = \Delta m / 2$

Hint:

Mass resolution $R = m/\Delta m$. Higher $R$ = better separation of adjacent masses.

Answer 1

The Correct Option is C

Step 1: Concept
Resolution in mass spectrometry.

Step 2: Meaning
Resolution $R$ quantifies the ability of a mass spectrometer to distinguish between two adjacent peaks of masses $m$ and $m+\Delta m$.

Step 3: Analysis
The standard definition of mass resolution is: \[ R = \frac{m}{\Delta m} \] A higher $R$ means the instrument can resolve peaks that are closer together. For example, $R = 10{,}000$ means masses differing by 1 Da can be resolved at $m/z = 10{,}000$. The reciprocal ($\Delta m/m$) would be the relative mass difference, not the resolution. Options (A) and (D) ignore the mass $m$ entirely.

Step 4: Conclusion
Resolution power in mass spectrometry: $R = m / \Delta m$. Final Answer: (C)