MPLUS2 Isotope Signature

Compare M+2 isotope intensity with caller-provided chlorine/sulfur references.

Description

An M+2 isotope-pattern screen compares a relative peak intensity with two supplied reference percentages.

An M+2 isotope-pattern screen compares a relative peak intensity with two supplied reference percentages. Nearest-reference labels indicate resemblance rather than elemental identification.^[1]

Compare M+2 isotope intensity with caller-provided chlorine/sulfur references.

When to use MPLUS2 Isotope Signature

Use this tool to compare M+2 isotope intensity with caller-provided chlorine/sulfur references.

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 MPLUS2 Isotope Signature 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 mPlusZeroIntensity, mPlusTwoIntensity, chlorineReferencePercent, sulfurReferencePercent, maximumDeviationPoints using the field table and calculation rules, then run the tool.
Read mPlusTwoPercent, signature. 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
mPlusZeroIntensity	M plus zero intensity	number	Required
mPlusTwoIntensity	M plus two intensity	number	Required
chlorineReferencePercent	Chlorine reference percent	number	Required
sulfurReferencePercent	Sulfur reference percent	number	Required
maximumDeviationPoints	Maximum deviation points	number	Required

Enter positive monoisotopic intensity, nonnegative M+2 intensity, finite chlorine/sulfur references and nonnegative percentage-point tolerance. Choose the nearest reference within tolerance, preferring chlorine on a tie; otherwise return unmatched.

observed%=100 Mplus2/M0; distance=|observed−reference|

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

Output field	Meaning	Value type
mPlusTwoPercent	M plus two percent	number
signature	Signature	string

json

{
  "input": {
    "mPlusZeroIntensity": 100,
    "mPlusTwoIntensity": 30,
    "chlorineReferencePercent": 32,
    "sulfurReferencePercent": 4,
    "maximumDeviationPoints": 5
  },
  "output": {
    "mPlusTwoPercent": 30,
    "signature": "chlorine-like"
  }
}

Limitations and assumptions

Other isotope contributions, multiple atoms and overlapping ions are ignored. References are caller-selected.

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 MPLUS1 Carbon Estimate: Estimate carbon number from M+1 intensity using a caller-supplied per-carbon isotope contribution. For a complementary task, use Isotopologue Distribution: Normalize M+0 through M+n isotopologues and count mean labeled carbons.

References

MPLUS2 Isotope Signature — tool.io

Similar or alternative tools

MPLUS1 Carbon Estimate
Estimate carbon number from M+1 intensity using a caller-supplied per-carbon isotope contribution.
Isotopologue Distribution
Normalize M+0 through M+n isotopologues and count mean labeled carbons.