The practical answer
HPLC reports purity as a UV peak-area percentage; MS confirms identity by molecular weight; AAA and net peptide content describe how much of the powder is peptide; KF measures water; TFA and acetate are counter-ions; GC measures residual solvents; LAL or BET measures bacterial endotoxin in EU. For each line, check the method, the numeric result, the unit, the lot and the date. [1] [2] [4]
Evidence, method & source dates ↓How to use this glossary
Certificates compress a lot of testing into short codes. Each abbreviation below has a plain definition, a note on what it does and does not show, and what to check on the certificate. Definitions are drawn from supplier quality pages, FDA and ICH documents. A term on a certificate is a claim about a lot; the glossary helps you read it, not verify it.
ICH Q7 says a certificate should list each test performed with its acceptance limits and numerical results, be dated and signed, and show the name and address of the original manufacturer, or of the laboratory that performed the analysis if the certificate is reissued by a reseller. [6] Use that as the baseline for every line.
Identity and purity terms
| Abbreviation | Stands for | What it shows | What to check |
|---|---|---|---|
| HPLC | High-performance liquid chromatography | Purity as the main peak's share of total UV peak area, usually at 210 to 220 nm [1] [2] | Wavelength, method conditions, chromatogram |
| RP-HPLC / UHPLC | Reversed-phase HPLC / ultra-high-performance LC | The separation GenScript names for measuring peptide purity [3] | Which mode and column |
| Area % | Peak area percentage | A ratio of peak areas, not a weight of peptide [1] [3] | Whether impurities are listed individually |
| MS | Mass spectrometry | Molecular weight, used to confirm identity [1] [2] | Observed vs theoretical mass, same lot |
| ESI-MS | Electrospray ionisation mass spectrometry | A common MS technique for peptide molecular weight [2] | Spectrum attached, not just "conforms" |
| LC-MS | Liquid chromatography with mass spectrometry | MS used as a detector after the HPLC separation [7] | Whether impurity peaks were also identified |
| [α] or OR | Optical rotation | Listed by Bachem as an identity test [1] | Value, concentration, solvent, temperature |
| Optical / chiral purity | Content of correct vs incorrect enantiomers | Whether the right stereoisomer predominates [1] | Method and limit |
Quantity and composition terms
| Abbreviation | Stands for | What it shows | What to check |
|---|---|---|---|
| NPC | Net peptide content | Percentage of peptide relative to non-peptidic material, mostly counter-ions and moisture [1] | Method (often AAA) and whether label mass is gross or net |
| AAA | Amino acid analysis | Peptide is hydrolysed into amino acids to quantify content; gives no sequence information [1] | Result as % and the reference used |
| KF | Karl Fischer titration | Water content [1] | Result in %, analysis date |
| TFA | Trifluoroacetic acid (trifluoroacetate) | A counter-ion that can be firmly bound to the peptide [1] | Whether TFA content is reported and the salt form stated |
| AcOH / acetate | Acetic acid / acetate salt | Alternative counter-ion, measured by HPLC or ion chromatography [1] | Content result if the label says acetate |
| IC | Ion chromatography | Used to measure counter-ions such as residual TFA [1] | Analyte and unit |
| MW | Molecular weight | Theoretical mass of the sequence and salt form | Whether it includes the counter-ion |
Safety, contaminant and method terms
| Abbreviation | Stands for | What it shows | What to check |
|---|---|---|---|
| GC | Gas chromatography | Residual solvent content [1] | Which solvents, ppm results |
| LAL | Limulus amebocyte lysate test | Bacterial endotoxin; FDA describes it as another name for the bacterial endotoxins test [4] | Method type and result in EU |
| BET | Bacterial endotoxins test | Same test family as LAL [4] | Gel-clot, turbidimetric, colorimetric or chromogenic [4] |
| EU | Endotoxin unit | FDA's unit of endotoxin activity [4] | EU per mg or per mL, and the limit used |
| DL / QL | Detection limit / quantitation limit | Lowest amount detectable / quantifiable with suitable precision and accuracy [5] | Whether "not detected" states the limit |
| LOD | Loss on drying or limit of detection, depending on the document | Ambiguous on its own; ICH Q2(R2) itself uses DL for detection limit [5] | Ask which meaning the certificate uses |
| Orthogonal method | An independent second technique | ICH Q2(R2) recommends combining procedures when one does not discriminate enough [5] | Whether purity and identity used different techniques |
Document and laboratory terms
| Term | Meaning | What to check |
|---|---|---|
| COA / CoA | Certificate of analysis: dated test results for a batch [6] | Lot, date, signature, laboratory name |
| Lot / batch | The production unit the certificate describes [6] | Matches the vial label exactly |
| Retest date | Date when material should be re-examined [6] | Not the same as an expiry date |
| Expiry date | Date after which material should not be used, under defined storage [6] | Storage condition stated with it |
| ISO/IEC 17025 | The standard that ILAC MRA signatory bodies use to accredit testing laboratories [8] | Accreditation body, certificate number and scope |
| ILAC MRA | International arrangement linking accreditation bodies [8] | Use its signatory search to confirm the body |
Where to go deeper on this site
- Reading the whole certificate in order: How to read a peptide certificate of analysis.
- Purity vs net peptide content and why both matter: Peptide purity vs peptide content.
- TFA and acetate counter-ions: the salt form guide.
- GC, ppm and solvent classes: the residual solvents and elemental impurities guide.
- Checking a laboratory's accreditation scope: the ISO 17025 verification guide.
- Retest and expiry dates: the retest date vs expiry date guide.
Questions before you decide
What does HPLC mean on a peptide COA?
High-performance liquid chromatography. It usually reports purity as the main peak's share of UV peak area, not as a weight of peptide.
What is the difference between LAL and BET?
FDA describes the bacterial endotoxins test as also termed the LAL test. Results are reported in endotoxin units (EU).
What does KF mean on a certificate?
Karl Fischer titration, a method for water content. It helps explain why net peptide content is below 100%.
Check the underlying evidence
Sources & review dates
- Bachem: quality control of amino acids and peptides, a guide ↗Accessed 29 Oct 2026
- GenScript: peptide quality control and report interpretation ↗Accessed 29 Oct 2026
- GenScript: recommended peptide purity levels and applications ↗Accessed 29 Oct 2026
- FDA: Bacterial Endotoxins/Pyrogens, Inspection Technical Guide 40 (March 1985, archived) ↗Accessed 29 Oct 2026
- ICH Q2(R2): Validation of Analytical Procedures (adopted 1 November 2023) ↗Accessed 29 Oct 2026
- ICH Q7: Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients (Step 4, 10 November 2000) ↗Accessed 29 Oct 2026
- Thermo Fisher: using mass spectrometry for oligonucleotide and peptide analysis ↗Accessed 29 Oct 2026
- ILAC: ILAC MRA and signatories ↗Accessed 29 Oct 2026
Sources are documentary evidence. They do not establish firsthand testing of a listed supplier.