1. What is a Mass Spec Mass Calculator?

Definition: This calculator determines the mass-to-charge ratio (m/z) of ions in mass spectrometry based on molecular mass, charge state, and proton mass.

Purpose: It helps researchers and analysts interpret mass spectrometry data by calculating the expected m/z values for charged molecules.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( m/z \) — Mass-to-charge ratio
• \( M \) — Molecular mass (Daltons)
• \( z \) — Charge state (unitless)
• \( H \) — Proton mass (1.007276 Da)

Explanation: The molecular mass plus the mass of added protons is divided by the charge state to give the m/z ratio observed in mass spectrometry.

3. Importance of Mass-to-Charge Ratio

Details: The m/z ratio is fundamental to mass spectrometry as it determines how ions are separated and detected in the mass analyzer.

4. Using the Calculator

Tips: Enter the molecular mass in Daltons, charge state (typically 1-10 for ESI), and proton mass (default 1.007276 Da). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for charge states?
A: In electrospray ionization (ESI), small molecules typically have z=1, while proteins can have z=5-20 or more.

Q2: Why is proton mass important?
A: Each charge comes from adding or removing a proton (H+), so its mass affects the total mass of the ion.

Q3: How accurate is this calculation?
A: Very accurate for singly charged ions. For multiply charged ions, isotope distributions become more complex.

Q4: Can this calculate for negative ions?
A: Yes, use negative z values (e.g., z=-1 for [M-H]-) and the calculator will handle it correctly.

Q5: What about other adducts besides protons?
A: For other adducts (e.g., Na+, K+), adjust the proton mass to the mass of your specific adduct.