HPLC versus LC-MS
Why purity and identity are different analytical questions.
Index
Research library
Every article on this site, with an original summary and the sources it cites. Written for readers who need to interpret a document rather than produce one.
Featured foundation articles
These longer foundation guides explain the analytical framework used throughout the library. Full reference lists appear at the foot of each article; use the A–Z index and practical explainers below to browse the complete collection.
Looking for a specific compound?
Browse the Peptides A–Z index for 26 compound and mixture guides, including BPC-157, GHK-Cu, MOTS-c, Semax, Selank, semaglutide, tirzepatide and retatrutide. Each page separates published evidence from batch-level analytical proof.
-
Research peptides in the UK: independent guide
Terminology, evidence, HPLC and LC-MS, COAs, batch checks, storage and a consistent framework for comparing UK suppliers.
Sources IUPAC terminology; ICH Q2(R2); Eurachem; UKAS; HSE COSHH.
-
BPC-157: research overview and evidence limits
A preclinical-evidence overview with exact identity, COA and batch questions kept separate from unsupported human claims.
Sources PubMed literature index; MHRA Products registry.
-
TB-500 and thymosin beta-4: what is the difference?
Why the informal label TB-500 is not a sufficient chemical identity and what sequence and mass evidence should clarify.
Sources PubMed thymosin beta-4 literature; IUPAC terminology.
-
GHK-Cu: research overview and analytical questions
The copper-binding tripeptide, the limits of published models, and why copper content and chromatographic purity are separate results.
Sources Pickart and Margolina; PubMed-indexed reviews.
-
CJC-1295 with DAC versus “no DAC”
A naming and identity guide explaining why “no DAC” is not simply a minor option on the same compound.
Sources Teichman et al.; PubMed; IUPAC terminology.
-
Understanding peptides in laboratory research
What a peptide is, how sequence, terminal chemistry and modifications define identity, how synthetic peptides are made and purified, and why laboratory materials are described in a completely different vocabulary from medicines.
Sources IUPAC-IUB nomenclature; Merrifield 1963; Behrendt et al. 2016; Manning et al. 2010; HSE COSHH.
-
Peptide testing and verification, method by method
Identity testing versus purity testing; what an HPLC area percentage really is; how LC-MS confirms molecular weight; the other tests that legitimately appear on a report; and the seven limitations you should assume are present in any result.
Sources ICH Q2(R2) and Q3A(R2); Eurachem 2014; IUPAC mass spectrometry terms 2013; Fenn et al. 1989; Snyder et al. 2010; ISO/IEC 17025:2017.
-
How to read a certificate of analysis
A field-by-field walkthrough: laboratory identity, sample identity, batch number, method section, chromatogram, results against specifications, dates and authorisation — followed by thirteen warning signs and a printable checklist.
Sources ISO/IEC 17025:2017; ICH Q2(R2); Eurachem 2014; Snyder et al. 2010; UKAS.
-
Batch traceability: codes, labels and custody
What a batch is and why the definition changes what a result means; how to read batch codes; the five-point label-to-report match; chain of custody; verification records; what lookup portals establish; and the three distinct meanings of a broken chain.
Sources ISO/IEC 17025:2017; OECD GLP principles; ISO 9001:2015; WHO GMP main principles; UKAS.
-
Identity and purity are two different questions
A high purity figure says nothing about whether the material is the compound named on the label. What each test establishes on its own, the order to read them in, and three certificate fragments compared.
Sources Eurachem 2014; ICH Q2(R2); IUPAC mass spectrometry terms 2013.
-
What mass spectrometry can and cannot tell you
Charge states and the mass-to-charge ratio, monoisotopic versus average mass, what isotope patterns reveal, and the five situations in which a correct mass is consistent with the wrong molecule.
Sources IUPAC mass spectrometry terms 2013; Fenn et al. 1989; Steen & Mann 2004.
-
Peak purity, net peptide content and water content
Three numbers, three different questions. Why counter-ions and residual water sit outside a chromatographic percentage, what basis a stated milligram quantity uses, and what a certificate reporting only purity leaves unknown.
Sources Andrushchenko et al. 2007; Rutherfurd & Gilani 2009; Manning et al. 2010; Eurachem 2014.
-
How to evaluate an analytical claim
A five-element test producing three verdicts — verifiable, partially verifiable, unsupported — plus seven common phrases that assert less than readers take from them, and how to write a conclusion that separates document from material.
Sources Eurachem 2014; ISO/IEC 17025:2017; UKAS.
Practical explainers
Testing, terminology and UK research rules
Purity versus content
Why 99% peak-area purity is not 99% of the vial mass.
COA warning signs
Fifteen document checks and how to write a fair conclusion.
Third-party testing
Laboratory independence, sampling, scope and traceability.
Research use only
What the UK label means and what it cannot establish.
UK laws and imports
Accurate classification, customs records and institutional checks.
Sourcing
How we cite
We prefer primary literature, standards documents and accreditation bodies over secondary summaries. Where a standard is paywalled we cite it by number so that it can be located, rather than reproducing its text. Citing a standard describes a principle — it never implies that a supplier, laboratory or product complies with it. Our full approach is set out in about and editorial standards.
A small number of external educational pages are referenced across these articles:
- Peptide testing and verification overviewexternal
- Peptide testing glossaryexternal
- Batch verification recordsexternal