Peptide purity and peptide content answer different questions. In the supplied Semax report, 99.18% is chromatographic area purity and 9.98 mg is measured content per vial; keep their bases separate.
Read three numbers on one report
| Entry | Value | Meaning |
|---|---|---|
| Vial label | 10 mg | Nominal labelled amount |
| Chromatographic purity | 99.18% | Main-component area fraction under the method |
| Measured content | 9.98 mg | Reported Semax amount per vial |
These are transcriptions from report MA-SEM-0041, revision 01, lot SEM-41-3J7. Area percentage is not a mass fraction of all material in the vial. Net peptide content has a separate definition and may include peptide-related impurities; water and counterions need their own basis.Semax report (PDF) (opens in a new tab)Bachem analytical guide (opens in a new tab)
Which comparison is justified?
Using the reported figures, 9.98 mg ÷ 10 mg × 100 = 99.8% of the label claim. That is an arithmetic comparison of two stated masses, not another purity measurement. The 9.98 mg result lies within this report’s 9.00–11.00 mg content range.Semax report (PDF) (opens in a new tab)
The shortcut 10 mg × 99.18% gives 9.918 mg, but does not calculate the measured content. It assumes both that the label is a measured total mass and that area purity is the target’s mass fraction. Those assumptions are not supplied by the two entries. Multiplying the separately reported 9.98 mg by purity again also needs a justified assay basis.Semax report (PDF) (opens in a new tab)Bachem analytical guide (opens in a new tab)
Read each measurement on its own basis
The report’s 99.18% purity and 0.82% total related substances are chromatographic area percentages and sum to 100.00%. Its 4.38% Karl Fischer water result uses a different measurement basis; adding water to that area total mixes denominators. Loss on drying is another quantity: it measures mass lost under stated conditions and need not measure only water.Semax report (PDF) (opens in a new tab)USP — General Chapter 731: Loss on Drying (opens in a new tab)
| Method | Interpretation question |
|---|---|
| Amino-acid analysis | Which measured residues, recovery and interferences support the peptide calculation? |
| Quantitative NMR | Which integrated signal, reference amount and quantitative conditions were used? |
| Water-specific analysis | Which sample and denominator does the result describe? |
A result’s uncertainty is different from a specification tolerance or variation between vials. Ask which quantity an interval describes, and keep the sampling question separate. An instrument-method name alone does not resolve those details.Eurachem/CITAC — Quantifying uncertainty in analytical measurement (opens in a new tab)NIST sampling principles (opens in a new tab)
Sources and further detail
- Supplied Semax 10 mg certificate (opens in a new tab)
MA-SEM-0041, revision 01; task DMAS3J7; lot SEM-41-3J7. Document-specific facts are transcriptions, not authentication. The cited PDF was re-read on 3 October 2026 to check this transcription; its issuer and findings were not independently authenticated.
- Bachem — Quality control of amino acids and peptides (opens in a new tab)
Analytical background on chromatographic purity and peptide content; the numerical examples here are our own or transcribed from supplied reports.
- USP — General Chapter 731: Loss on Drying (opens in a new tab)
Public 2020 chapter preview, DOI 10.31003/USPNF_M99510_02_01. Used only for the definition, not as a complete current monograph or product-compliance assessment.
- Bunk and Lowenthal — Isotope-dilution LC-MS/MS amino acid analysis (opens in a new tab)
NIST-authored methods chapter (2019), DOI 10.1007/978-1-4939-9639-1_12. Quantification framework and hydrolysis limitations; no laboratory procedure reproduced.
- BIPM — Internal standard reference data for proton qNMR (opens in a new tab)
Rapport BIPM-2018/04, equation 1 and sections on signal selection, acquisition and traceability. Dimethyl sulfone guidance is not a universal peptide method.
- Metrohm — Volumetric and coulometric Karl Fischer titration (opens in a new tab)
Official explanation of iodine addition versus electrochemical generation. Vendor operating ranges are not used as universal validation limits.
- Eurachem/CITAC — Quantifying uncertainty in analytical measurement (opens in a new tab)
Third edition (2012), measurement specification, contribution identification and double-counting guidance. Listed as current by Eurachem on the source-check date; original examples avoid the guide's numerical errata.
- NIST/SEMATECH — Populations and sampling (opens in a new tab)
Statistical background on sample-to-population inference; the vial scenarios are original illustrations.
Revised from the existing source dossier on 3 October 2026. Supplied-report values are document transcriptions, not independent authentication or new measurements. Source notes identify the scope of each reference; this article has not undergone independent scientific peer review.