Fragment Tolerance PPM

Convert a fragment mass tolerance from daltons to ppm.

Description

A ppm tolerance expresses a mass-width allowance relative to a reference m/z.

A ppm tolerance expresses a mass-width allowance relative to a reference m/z. The same absolute allowance has a different ppm value at different masses.^[1]

Convert a fragment mass tolerance from daltons to ppm.

When to use Fragment Tolerance PPM

Use this tool to convert a fragment mass tolerance from daltons to ppm.

Prepare the canonical sequence, peptide assignments, fitted assay parameters or upstream measurements requested. Keep corresponding entries aligned, use the stated mass and signal units, and remove FASTA headers before entering sequence text.

How to use Fragment Tolerance PPM and understand its results

Prepare the canonical sequence, peptide assignments, fitted assay parameters or upstream measurements requested. Keep corresponding entries aligned, use the stated mass and signal units, and remove FASTA headers before entering sequence text.
Enter fragmentMz, toleranceDa using the field table and calculation rules, then run the tool.
Read tolerancePpm. 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
fragmentMz	Fragment mz	number	Required
toleranceDa	Tolerance da	number	Required

Enter positive fragment m/z and nonnegative absolute allowance on the same m/z numeric basis. Return the relative ppm allowance.

tolerancePpm=1,000,000×toleranceDa/fragmentMz

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

Output field	Meaning	Value type
tolerancePpm	Tolerance ppm	number

json

{
  "input": {
    "fragmentMz": 500,
    "toleranceDa": 0.01
  },
  "output": {
    "tolerancePpm": 20
  }
}

Limitations and assumptions

The field is named toleranceDa, but comparison with m/z requires a compatible charge convention. No charge conversion, peak error or instrument calibration is performed.

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 Peptide Mass Error Dalton: Calculate peptide mass error in daltons. For a complementary task, use Precursor MZ: Calculate peptide precursor m/z for a given integer charge.

References

Fragment Tolerance PPM — tool.io

Similar or alternative tools

Peptide Mass Error Dalton
Calculate peptide mass error in daltons.
Precursor MZ
Calculate peptide precursor m/z for a given integer charge.