How to Read a Peptide COA: HPLC Purity, Identity Testing, and SHR’s Batch Process

A certificate of analysis (COA) is a document issued by an independent analytical laboratory stating that a tested sample was analyzed using specified methods and produced specific results. In the context of research peptides, two analytical methods are standard: high-performance liquid chromatography (HPLC) for purity quantification, and identity confirmation through retention time matching and UV spectral comparison. Together, they establish two distinct things: that a sample is largely free of impurities, and that the dominant compound in that sample is what the label claims it to be.

The report is only as meaningful as three things: the independence of the laboratory that generated it, the match between the sample tested and the lot being purchased, and the completeness of the testing methods applied. A single purity number from an unverified source is not a COA in the analytical sense — it is an assertion. A COA from a named independent laboratory with full chromatographic data, identity confirmation, and signed approval by named responsible parties is a verifiable evidentiary document.

SHR uses TrustPointe Analytics LLC (Dorr, MI — Agilent Technologies powered) for independent analytical testing across its compound catalog. Reports are signed by the laboratory’s President and Managing Director and are batch-specific to the lot shipped.

High-performance liquid chromatography (HPLC) separates compounds in a dissolved sample by forcing the mixture through a column of stationary phase under high pressure. Compounds interact differently with the stationary phase: those that interact less travel faster through the column and exit first; those that interact more travel slower and exit later. A UV detector at the column outlet records the absorbance of eluting compounds over time, producing a chromatogram — a graph of absorbance (mAU) versus time (minutes).

Each peak on the chromatogram represents a compound present in the sample. The dominant peak should correspond to the target compound, appearing at a consistent and expected retention time — the time at which that specific compound elutes under the given method conditions. Purity is calculated as the area of the target peak divided by the total area of all detected peaks, expressed as a percentage.

What to look for in HPLC purity data:

• Purity percentage stated explicitly, alongside the method name or code
• Retention time of the dominant peak — it should match the reference standard run under the same conditions
• Chromatogram profile — a clean dominant peak with minor or absent secondary peaks
• System suitability result — confirms the instrument performed within specification during the run

For peptide research compounds, a purity of ≥98% by HPLC is the standard threshold for research-grade material.

From actual SHR batch data — Retatrutide (TrustPointe Analytics, sequence 1004_hmp_072125, acquired 2025-07-21):

Seven separate production lots were tested in a single analytical sequence alongside five bracketing reference standards. Results across all seven lots:

All seven lots passed at ≥98% purity. The retention time cluster of 6.14–6.19 minutes — tight and consistent across all lots and reference standards — confirms stable instrument performance and that the dominant compound in each lot elutes at the same time as the reference standard. Minor impurity peaks visible in the raw chromatograms (at approximately 4.8–5.5 minutes) contribute 0.087%–1.551% of total peak area, confirming Retatrutide dominates each sample.

HPLC purity analysis tells you how pure a sample is; it does not tell you what the dominant compound actually is. A 99% pure sample is only meaningful if that 99% is the compound you believe it to be.

Identity confirmation in HPLC-based COAs is established through two parallel methods:

Retention time (RT) identity: The target peak’s retention time is compared against a certified reference standard run under identical method conditions in the same analytical sequence. If the sample peak elutes at the same time as the reference standard, this constitutes identity confirmation by retention time. In TrustPointe’s reporting format, this result is expressed as a ratio — a value of 1.00 indicates the sample retention time matches the reference standard exactly within the tolerance window.

UV spectral match (ID by Spectral): The diode array detector (DAD) on the HPLC instrument records the full UV absorbance spectrum of each peak as it elutes — a plot of absorbance versus wavelength from approximately 200–400 nm. This spectrum is a molecular fingerprint unique to each compound’s electronic structure. The UV spectrum of the target peak is compared mathematically against the spectrum of the certified reference standard. TrustPointe reports this on a scale of 0–1000, where 1000 represents a perfect spectral correlation. A “Compound Spectra Confirm Result: Confirmed” notation accompanies the score.

From actual SHR batch data — BPC-157 10mg (Sample ID SPL-1189, TrustPointe Analytics, published 2025-06-20):

Reading this result: ID by RT of 1.00 means the sample peak elutes at the same time as the certified BPC-157 reference standard. ID by Spectral of 1000 means the UV spectrum of the sample peak is a perfect mathematical match to the reference standard — compound identity confirmed. Purity of 99.603% means 99.6% of the detected signal belongs to BPC-157. Coelution Control of 998 confirms no interfering compound is co-eluting under the target peak. System suitability of 0.8% RSD confirms the instrument was performing within acceptable precision limits during the run.

The report also includes a photograph of the physical sample vial submitted to the laboratory, tying the analytical data to a specific physical specimen with a visible lot identifier — an additional chain-of-custody marker.

A complete research peptide COA should include all of the following:

• Named independent laboratory — verifiable name, physical address, and contact information. Not the supplier’s internal lab.
• Named responsible parties — signed or attributed to named individuals (not anonymous or generic “laboratory staff”).
• Unique sample ID — traceable to the specific lot submitted for testing, not a representative batch.
• Publication or report date — confirming the test applies to a current batch.
• HPLC purity percentage with explicit method name or code.
• Retention time of the dominant peak — the raw number, not just a pass/fail notation.
• Identity by RT match against a certified reference standard run in the same sequence.
• Identity by UV spectral match against a certified reference standard, with score and confirmation status.
• System suitability result — confirming instrument precision during the run.
• Physical sample photograph — best practice; standard in TrustPointe’s process.

• A single purity number without supporting chromatographic data. Anyone can write “99% purity” in a document. Without the underlying retention time, peak area breakdown, and impurity profile, the number cannot be verified. The raw data is what makes the result auditable.
• No identity confirmation. HPLC purity confirms the proportion of each component in a sample; it does not confirm what the dominant component is. Without retention time matching and/or UV spectral confirmation against a certified reference standard, a high purity result only confirms that something in that vial is largely pure — not that the compound is what it claims to be.
• No named independent laboratory. A COA without a verifiable third-party laboratory is an internal document. Internal testing by the supplier is not a substitute for independent analytical verification.
• No date or batch-specific identifiers. A COA from a prior production run does not apply to the batch being purchased. Batch-specific documentation should be standard; generic or undated certificates apply to no particular sample.
• No system suitability data. Without a passing system suitability result, even raw chromatographic data cannot be confirmed as instrument-valid for that specific run.

Every compound in the Stackhaus Research catalog is tested by TrustPointe Analytics LLC prior to fulfillment. The process is batch-specific: each production lot is submitted as a physical sample to the laboratory, assigned a unique sample ID, and analyzed under a validated method before results are associated with that lot in SHR’s documentation.

For compounds with multiple concurrent production lots — as in the Retatrutide potency report referenced above, where seven lots were tested in a single analytical sequence — each lot receives individual purity and identity results. No aggregate or representative-batch approach is used in SHR’s testing process.

The reports are generated on Agilent HPLC instrumentation using diode array detection (DAD), with UV spectral matching performed against certified reference standards. Results are signed by TrustPointe’s President and Managing Director before the report is considered final and associated with a production lot.

COAs for current batches are available for download at stackhausresearch.com. Researchers can access batch-specific documentation for any active compound in the catalog at the time of their order.

All Stackhaus Research compounds are for research use only and are not for human use or consumption. This documentation is provided for research transparency and does not constitute a therapeutic claim.