Calculation Result
Summary Table
| Metric | Value |
|---|
Composition Graph
Calculator
Example Data Table
| Case | Input | Mode | Mass Type | Sample Mass | Volume | Purpose |
|---|---|---|---|---|---|---|
| 1 | Glycine | Single Amino Acid | Average | 25 mg | 10 mL | Introductory lab preparation |
| 2 | ACDEFGHIK | Peptide Sequence | Monoisotopic | 500 µg | 250 µL | Peptide stock planning |
| 3 | Tyrosine | Single Amino Acid | Average | 2 mg | 1 mL | Concentration check |
Formula Used
1) Molecular mass from formula
M = (C × mass of C) + (H × mass of H) + (N × mass of N) + (O × mass of O) + (S × mass of S)
2) Peptide formula from sequence
Peptide formula = Sum of free amino acid formulas − (n − 1) × H₂O
3) Moles from sample mass
moles = corrected sample mass / molar mass
4) Corrected sample mass
corrected sample mass = sample mass × (purity / 100)
5) Concentration
concentration = moles / solution volume
6) Mass-to-charge ratio
m/z = (neutral mass + charge × proton mass) / charge
Average mass uses mean isotopic atomic weights. Monoisotopic mass uses the most abundant isotope for each element. Sequence mode returns the complete peptide formula with terminal groups included.
How to Use This Calculator
- Choose single amino acid mode or peptide sequence mode.
- Select average or monoisotopic mass.
- Enter either one amino acid or a peptide sequence.
- Add sample mass, purity, volume, and charge state.
- Press Calculate Mass to show results above the form.
- Review molar mass, formula, moles, concentration, and m/z.
- Use the graph to inspect elemental composition visually.
- Export the summary as CSV or PDF when needed.
Frequently Asked Questions
1. What does this calculator measure?
It estimates molecular mass for one amino acid or a peptide sequence. It also reports formula, moles, concentration, and charge-adjusted m/z values.
2. What is the difference between average and monoisotopic mass?
Average mass uses natural isotope averages. Monoisotopic mass uses the most abundant isotope of each element. Mass spectrometry workflows often prefer monoisotopic values.
3. Does sequence mode include peptide bond water loss?
Yes. The calculator sums free amino acids and subtracts one water molecule for each peptide bond. That gives the neutral peptide formula.
4. Can I enter spaces or lowercase letters in sequences?
Yes. Spaces and line breaks are removed automatically, and lowercase letters are converted to uppercase before the calculation runs.
5. What units are supported for sample mass and volume?
Mass units include g, mg, µg, and ng. Volume units include L, mL, and µL. The calculator converts them internally.
6. Why is purity included?
Purity corrects the entered sample mass. A 90% pure sample contributes less actual analyte than a 100% pure sample of the same weight.
7. What does the graph show?
The graph displays elemental composition counts for carbon, hydrogen, nitrogen, oxygen, and sulfur. It helps compare molecular makeup at a glance.
8. Is this suitable for every biochemical workflow?
It is a strong educational and planning tool. Specialized workflows with modifications, salts, or protecting groups may need additional adjustments.