Nominal Mass Defect

Determine signed nominal-minus-exact molecular mass defect.

Description

Nominal mass defect compares a nominal reference with an exact mass.

Nominal mass defect compares a nominal reference with an exact mass. Its sign depends on the nominal-minus-exact convention used here.^[1]

Determine signed nominal-minus-exact molecular mass defect.

When to use Nominal Mass Defect

Use this tool to determine signed nominal-minus-exact molecular mass defect.

Prepare the measured profile, formula counts, upstream model outputs or caller-defined reference criteria requested. Keep paired entries aligned and units, sample basis and preprocessing consistent.

How to use Nominal Mass Defect and understand its results

Prepare the measured profile, formula counts, upstream model outputs or caller-defined reference criteria requested. Keep paired entries aligned and units, sample basis and preprocessing consistent.
Enter nominalMassDa, exactMassDa using the field table and calculation rules, then run the tool.
Read nominalMinusExactDa, sign. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
nominalMassDa	Nominal mass da	number	Required
exactMassDa	Exact mass da	number	Required

Enter positive finite masses. Return signed difference and positive, negative or zero classification. Nominal mass is not required to be an integer.

defect=nominalMass−exactMass

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
nominalMinusExactDa	Nominal minus exact da	number
sign	Sign	string

json

{
  "input": {
    "nominalMassDa": 100,
    "exactMassDa": 100.1
  },
  "output": {
    "nominalMinusExactDa": -0.09999999999999432,
    "sign": "negative"
  }
}

Limitations and assumptions

No elemental composition, isotope pattern or charge correction is inferred.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Kendrick Mass Defect: Convert exact mass to a caller-defined Kendrick repeat-unit basis. For a complementary task, use Monoisotopic Formula Mass: Sum neutral monoisotopic mass from C/H/N/O/S/P atomic compositions.

References

Nominal Mass Defect — tool.io

Similar or alternative tools

Kendrick Mass Defect
Convert exact mass to a caller-defined Kendrick repeat-unit basis.
Monoisotopic Formula Mass
Sum neutral monoisotopic mass from C/H/N/O/S/P atomic compositions.