1. What is Mass Error?

Mass error is the difference between a measured mass and its theoretical value, expressed in parts per million (ppm). It's commonly used in mass spectrometry to assess the accuracy of mass measurements.

2. How Does the Calculator Work?

The calculator uses the mass error equation:

Where:

• \( \text{Measured Mass} \) — The experimentally determined mass (Da)
• \( \text{Theoretical Mass} \) — The calculated exact mass (Da)

Explanation: The equation calculates the relative difference between measured and theoretical masses, scaled to parts per million for easier interpretation.

3. Importance of Mass Error Calculation

Details: Mass error is crucial in mass spectrometry for compound identification, method validation, and instrument calibration. Lower ppm values indicate higher measurement accuracy.

4. Using the Calculator

Tips: Enter both masses in Daltons (Da). For best results, use high-precision mass values (4+ decimal places). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is an acceptable mass error in ppm?
A: Typically <5 ppm is good for small molecules, <2 ppm is excellent. For high-resolution instruments, <1 ppm is often achievable.

Q2: Why use ppm instead of absolute mass difference?
A: ppm provides a relative error that's comparable across different mass ranges, unlike absolute differences which vary with mass.

Q3: How does mass accuracy affect compound identification?
A: Lower mass errors reduce the number of possible molecular formulas, increasing confidence in identification.

Q4: Can this calculator be used for m/z values?
A: Yes, it works for both mass-to-charge ratios (m/z) and neutral masses, provided both values are in the same units.

Q5: What factors contribute to mass error?
A: Instrument calibration, resolution, peak shape, sample purity, and data processing methods all affect mass error.