MS ADDUCT &
EXACT MASS CALCULATOR
Molecule Definition
Awaiting Molecule Data
Precision Mass Analysis
Our Advanced MS Adduct Calculator is built for the rigorous demands of analytical chemistry. Unlike basic mass calculators, we utilize a multi-isotope database (IUPAC standards) to model exact masses and theoretical isotopic envelopes for any molecular formula or peptide sequence.
Exact Mass Database
Native support for all 118 elements using high-precision monoisotopic weights.
Isotope Modeling
Dynamic isotopic profile visualization powered by canvas-based abundance analysis.
Reverse Search
Identify formulas from observed m/z values with configurable PPM error margins.
Adduct Classification
Support for common ESI/APCI adducts including Na+, K+, Cl-, and AcO-.
Peptide Engine
Automated Y-ion and B-ion fragmentation modeling for protein identification.
Computational Speed
High-speed combinatorial search algorithm for real-time formula matching.
MASTERING MASS
SPECTROMETRY ADDUCTS
In Electrospray Ionization (ESI), molecules rarely appear as neutral species. They typically gain or lose protons or associate with charge carriers like Sodium ($[M+Na]^+$) or Potassium. Understanding these adducts is vital for correct formula assignment.
01. Monoisotopic vs Average
Monoisotopic mass (used here) is the mass of the species containing only the most abundant isotope of each element. Average mass is the weighted mean based on natural abundance—useful for low-res MS but unsuitable for formula identification.
02. Understanding PPM Error
High-res MS (Orbitrap, Q-TOF) typically yields errors within 2-5 Parts Per Million (PPM). Our reverse search allows you to filter formulas within this tight window to eliminate false positives.
FREQUENTLY ASKED QUESTIONS
Q. Why do I see [M+Na]+ in my spectrum?
Sodium is a common impurity in glassware and solvents. Oxygen-rich molecules (ethers, alcohols, ketones) have a high affinity for Na+ cations during ionization.
Q. What is the Double Bond Equivalent (DBE)?
DBE (also called unsaturation degree) calculates the total number of rings and double bonds in a formula. A DBE below 0 indicates an impossible chemical structure.
Q. Can this handle multivalent charges?
Yes. By specifying the charge (z) in the settings, the calculator correctly adjusts the m/z ratio ($m/z = [m+H]/1$, $[m+2H]/2$, etc.).