1. What is Accurate Mass?

Accurate mass refers to the calculated mass of a molecule based on the exact masses of its constituent isotopes. It's different from nominal mass which uses integer mass numbers.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( AM \) — Accurate mass in atomic mass units (u)
• \( A_i \) — Number of atoms of element i
• \( M_i \) — Atomic mass of element i (u)

Explanation: The calculator sums the products of each element's atomic mass multiplied by the number of atoms of that element in the molecule.

3. Importance of Accurate Mass

Details: Accurate mass calculations are essential in mass spectrometry for identifying molecular formulas, distinguishing between isobaric compounds, and confirming molecular structures.

4. Using the Calculator

Tips: Enter elements in the format "ElementCount" separated by commas (e.g., "C6,H12,O6" for glucose). The calculator recognizes common elements and uses their exact isotopic masses.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between accurate mass and nominal mass?
A: Accurate mass uses exact isotopic masses (e.g., 1.007825 u for H), while nominal mass uses integer mass numbers (1 u for H).

Q2: How precise should my accurate mass be?
A: For identification purposes, mass accuracy of 5 ppm or better is typically needed in high-resolution mass spectrometry.

Q3: Does this calculator consider isotopic distributions?
A: No, it calculates monoisotopic mass using the most abundant isotope for each element.

Q4: What elements are supported?
A: The calculator includes H, C, N, O, F, P, S, Cl, Br, and I. More can be added as needed.

Q5: How does this differ from molecular weight?
A: Molecular weight typically uses average atomic masses, while accurate mass uses exact isotopic masses.