Methodological standard · §5
CEI-MS-02 — system suitability and acceptance criteria
The performance the system must demonstrate, and the criteria a result must meet to be reportable.
§5System suitability and acceptance criteria
§5.1System suitability
Table 1. System suitability criteria. A determination is reportable only where every criterion is met at the time of analysis.
| Parameter | Criterion | What it establishes |
|---|---|---|
| Calibration residual across the acquisition range | ≤ 5 ppm | Mass accuracy |
| Resolving power at m/z 1000 | ≥ 5 000; ≥ 30 000 for near-isobaric pairs | Discrimination capability |
| Charge states observed | ≥ 2 | Deconvolution reliability |
| Sequence coverage, peptides ≤ 20 residues | ≥ 80 % of interresidue bonds | Sequence confirmation |
| Sequence coverage, peptides > 20 residues | ≥ 60 % of interresidue bonds | Sequence confirmation |
§5.2Acceptance criteria
- Identity is confirmed where the deconvoluted average mass agrees with the expected value within 2 Da for peptides below 3 kDa and within 3 Da above 3 kDa, and sequence coverage meets the stated threshold.
- Mass agreement alone, without sequence coverage, is recorded as "composition consistent" and not as "identity confirmed".
- Where the expected mass is not public, identity cannot be confirmed under this standard and the Institute records the compound as identity-unconfirmable rather than as failing.
- For the bremelanotide/melanotan-II pair, resolution below 5 000 at m/z 1025 does not distinguish the two compounds and any identity claim so obtained is recorded as not conformant.
§5.3Limitations
Compound Evidence Institute · CEI-MS-02/5 · https://compoundevidence.com/methods/lcmsms-identity/acceptance-criteria/ · retrieved 30 July 2026