1. What is Mass Accuracy?

Mass accuracy is a measure of how close the observed mass (OM) is to the experimental mass (EM) of a molecule, typically expressed in parts per million (ppm). It's a crucial parameter in mass spectrometry for compound identification.

2. How Does the Calculator Work?

The calculator uses the mass accuracy formula:

Where:

• \( EM \) — Experimental Mass (Da)
• \( OM \) — Observed Mass (Da)
• \( 10^6 \) — Conversion factor to ppm

Explanation: The formula calculates the relative error between experimental and observed mass in parts per million.

3. Importance of Mass Accuracy

Details: High mass accuracy is essential for confident compound identification in mass spectrometry. Lower ppm values indicate better agreement between observed and theoretical masses.

4. Using the Calculator

Tips: Enter both masses in Daltons (Da). The calculator will compute the mass accuracy in ppm. Values below 5 ppm are generally considered excellent for most applications.

5. Frequently Asked Questions (FAQ)

Q1: What is a good mass accuracy value?
A: For high-resolution mass spectrometers, values < 5 ppm are typically considered good, while < 2 ppm is excellent.

Q2: How does mass accuracy differ from mass precision?
A: Accuracy refers to closeness to the true value, while precision refers to reproducibility of measurements.

Q3: What factors affect mass accuracy?
A: Instrument calibration, resolution, sample preparation, and environmental conditions can all impact mass accuracy.

Q4: Why use ppm instead of absolute mass difference?
A: ppm provides a relative measure that's comparable across different mass ranges, unlike absolute differences.

Q5: How often should I calibrate my mass spectrometer?
A: Follow manufacturer recommendations, typically before each run or daily for optimal mass accuracy.