1. What is Mass Accuracy Calculator for Water?

Definition: This calculator determines the mass accuracy in parts per million (ppm) between measured and theoretical mass of water molecules.

Purpose: It helps chemists and mass spectrometry users evaluate the precision of their mass measurements.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \Delta m \) — Mass accuracy (ppm)
• \( m_m \) — Measured mass (u)
• \( m_t \) — Theoretical mass of water (18.01528 u)

Explanation: The difference between measured and theoretical mass is divided by theoretical mass and scaled to ppm.

3. Importance of Mass Accuracy Calculation

Details: Mass accuracy is crucial in analytical chemistry for identifying compounds, assessing instrument performance, and validating experimental results.

4. Using the Calculator

Tips: Enter the measured mass in atomic mass units (u) and theoretical mass (default 18.01528 u for water). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a good mass accuracy value?
A: For high-resolution mass spectrometry, values < 5 ppm are typically excellent, while < 10 ppm is generally acceptable.

Q2: Why is water used as a reference?
A: Water is commonly used for calibration due to its well-defined mass and ubiquity in mass spectrometry.

Q3: Can I use this for other molecules?
A: Yes, simply change the theoretical mass to match your target molecule.

Q4: What affects mass accuracy?
A: Instrument calibration, resolution, peak shape, and signal-to-noise ratio all impact mass accuracy.

Q5: What does negative ppm mean?
A: Negative values indicate your measured mass is lower than theoretical, while positive means it's higher.