Calcolatore Inibizione Enzimatica — Formula
## Mass Accuracy in Mass Spectrometry
Mass accuracy is the difference between the measured and theoretical mass of an ion, expressed in parts per million (ppm). It determines how confidently you can assign a molecular formula.
### Formula
**Error (ppm) = (m_measured - m_theoretical) / m_theoretical × 10⁶**
Modern high-resolution instruments achieve < 2 ppm (Orbitrap) or < 1 ppm (FT-ICR). Time-of-flight (TOF) instruments typically achieve 2-5 ppm.
Mass accuracy is the difference between the measured and theoretical mass of an ion, expressed in parts per million (ppm). It determines how confidently you can assign a molecular formula.
### Formula
**Error (ppm) = (m_measured - m_theoretical) / m_theoretical × 10⁶**
Modern high-resolution instruments achieve < 2 ppm (Orbitrap) or < 1 ppm (FT-ICR). Time-of-flight (TOF) instruments typically achieve 2-5 ppm.
Esempio Risolto
Glucose [M+H]+ measured at 180.0637, theoretical 180.0634.
- Error = (180.0637 - 180.0634) / 180.0634 × 10⁶
- Error = 0.0003 / 180.0634 × 10⁶ = 1.67 ppm
- Error in mDa = 0.3 mDa