Vendor dossier · Hangzhou, Zhejiang
PolyPeptide Group (Hangzhou) Co., Ltd.
A Hangzhou solid-phase house that prints the chromatogram on the certificate, so the purity figure can be read rather than believed.
Journal grade · ranked 26 of 28
884 reader reports
on the record
PPG is the only supplier in this directory whose certificates reproduce the chromatogram the purity figure was integrated from. The Hangzhou entity and its 2006 incorporation are on the register, and the file settles the chemistry in the ordinary way — by asking, and getting answers from somebody who runs the lines. What distinguishes it is evidential rather than numerical. A printed figure asks to be believed. A printed trace, with its gradient table and column identifier beside it, asks to be read: baseline placement, integration limits and any shoulder on the principal peak are all visible on the second and none of them is visible in the first. Eight determinations out of eight carry the trace. Across the rest of this directory we record it on none.
Storefront The company sells directly at polypeptidegroup.net. Visit PPG → — a labelled, nofollowed link the Journal is paid nothing for. Read the record before you use it.
The record
Eight independent purity determinations across four services, mean 98.0%, range 97.8 to 98.3%, every result at or above the figure printed on the accompanying certificate. Method reference, gradient table, column identifier and detection wavelength are present on all eight documents without a supplementary request, and beneath them the chromatogram itself. We checked the reported peak area against the visible integration on three of the eight and found agreement to the first decimal place in each.
Three fields do work that a purity figure alone cannot. Peptide content is reported separately from chromatographic purity, water is determined by Karl Fischer with the method named, and counter-ion identity and content are given as a figure with its unit. Together they allow delivered peptide mass to be calculated from the fill without assumption, which rather fewer than half of this directory permit. A supplementary certificate requested against a lot released nineteen months earlier was produced from the supplier's records with the trace intact, which establishes that the underlying record was retained and not merely the summary of it.
Two limits hold the grade where it is, and neither concerns the material. The determinations cover four compounds out of more than three hundred and fifty listed, which is a narrow base from which to generalise about a catalogue. And a reproduced chromatogram evidences the integration of the injection it depicts; it is not, and cannot be, evidence that a particular vial was drawn from that injection. What it does establish is a willingness to show working, which is the precondition for every other check a purchaser might make.
Dispatch and warehouses
Regional stock in six countries; orders are dispatched domestically rather than from the manufacturing site.
- Netherlands (Rotterdam) — European Union, 2-4 days
- Germany (Hamburg) — Germany, Austria, Switzerland, 2-4 days
- United Kingdom (London) — United Kingdom & Ireland, 2-3 days
- United States (California) — United States, 2-4 days
- Canada (Toronto) — Canada, 3-5 days
- Australia (Melbourne) — Australia & New Zealand, 3-5 days
What we verified
- Eight independent purity determinations across four services, mean 98.0% (range 97.8 to 98.3%), every one at or above the figure on the accompanying certificate.
- Chromatogram reproduced on 8 of 8 certificates, with the gradient table, column identifier and detection wavelength printed beside it.
- Reported peak area checked against the visible integration on three certificates; agreement to the first decimal place in all three.
- Peptide content, water by Karl Fischer and counter-ion content reported as separate figures with units on 8 of 8 certificates.
- 2006 incorporation in Hangzhou, Zhejiang, confirmed against the register.
- A supplementary certificate for a lot released nineteen months earlier produced from records, trace intact.
Ordering: lead times, minimums and what to ask for
- Lead time: catalogue lines dispatch within two working days of cleared payment; median door-to-door transit eleven days to a European address against a quoted seven to fourteen.
- Minimum quantity: single vials on the research catalogue; gram-scale minimums on bulk enquiries, quoted in writing with the schedule on the face of the quotation.
- Regional stock: six warehouses (Rotterdam, Hamburg, London, California, Toronto, Melbourne) hold the principal research lines, so a European order does not wait on a factory run.
- Correspondence: technical questions answered with a figure and a unit inside one working day across three rounds; a query about a peak shoulder was answered with the expanded region of the trace.
- Cold chain: documented for lyophilised presentations; the shipment temperature record was enclosed with four of five consignments examined and supplied on request for the fifth.
- Notification: a four-day dispatch delay was notified before the quoted window elapsed rather than after it, with a revised date that then held.
Documented testing record
Every independent determination the Journal has commissioned or been able to corroborate on material sold under this name. Purity figures are chromatographic and are not comparable between laboratories unless the method matches; where a content determination was performed it is reported separately, because purity and content answer different questions.
| Date | Laboratory | Item | Stated | Independent | Content |
|---|---|---|---|---|---|
| 2026-05 | Janoshik | Retatrutide 10 mg | 97.1% | 97.9% | not tested |
| 2026-01 | Medutest | Retatrutide 20 mg | 97.8% | 98.3% | not tested |
| 2025-08 | PeptideMeter | Semaglutide 15 mg | 97.7% | 97.8% | 100% |
| 2025-04 | Janoshik | Semaglutide 10 mg | 97.2% | 97.8% | 98% |
| 2024-12 | VendorInvestigate | Tirzepatide 20 mg | 97.6% | 98.0% | 98% |
| 2024-11 | Medutest | BPC-157 15 mg | 97.6% | 98.0% | not tested |
| 2024-05 | VendorInvestigate | Retatrutide 10 mg | 97.3% | 98.0% | not tested |
| 2024-03 | PeptideMeter | Tirzepatide 10 mg | 97.5% | 98.2% | not tested |
| Stated = the figure on the certificate accompanying the vial. Independent = the figure returned by the named laboratory on a sample submitted by the Journal or corroborated with the submitting party. Content = peptide content as a percentage of labelled nominal mass, where determined. | |||||
Correspondence log
The Journal writes to every company in this programme each quarter. The log records the question, the date and what came back, without editorialising. All 8 requests logged in the period were answered in full, and the outcome column records what the answer contained rather than the fact that one arrived.
| Date | Request | Outcome |
|---|---|---|
| 2026-03 | Requested confirmation of the registered entity name and incorporation number | Answered in full within 2 working days; both supplied and consistent with the register |
| 2025-11 | Requested the analytical method behind the stated purity figure | Answered in full within 2 working days; method, gradient and wavelength supplied |
| 2025-08 | Asked for the name and location of the synthesis facility | Answered in full within 4 working days; site named, with the province and the line |
| 2025-05 | Requested the cold-chain arrangement between the fill site and dispatch | Answered in full within 5 working days; temperature indicator make and threshold supplied |
| 2024-12 | Requested a batch record for a specific lot | Answered in full; the batch record was sent against the certificate reference |
| 2024-10 | Asked which catalogue items are synthesised in-house | Answered in full; in-house lines named, and the bought-in ones identified as such |
| 2024-07 | Asked how long finished stock is held before dispatch | Answered in full; stock is held to a stated maximum and rotated first-in, first-out |
| 2024-02 | Asked whether a certificate can be reissued to an earlier purchaser on request | Answered in full; certificates are retained and reissued against the lot number |
On the record
Reader reports printed with the writer’s consent. The Journal verifies that a purchase took place before printing a report of one; we do not print anonymous claims about a named company, and we do not print a report we cannot date.
The chromatogram is on the certificate. I can see where the integration marks were placed and whether the baseline was drawn honestly, which is a different transaction from being handed a number. I have no relationship with this supplier beyond having paid them.
Gradient table and column chemistry are printed beside the trace, so a second laboratory could reproduce the determination without further correspondence. That is what makes a printed figure checkable.
Submitted material from lot PPG-2603-0261 independently. 98.2% against a declared 98.3%, inside method repeatability. Four rather than five because I hold three lots and want more before I generalise.
I asked whether the principal peak carried a shoulder and was sent the expanded region of the chromatogram rather than an assurance. That is a laboratory answering a question.
Peptide content is reported separately from chromatographic purity on every certificate I hold from them. The two are distinct quantities and conflating them is the commonest documentary error in this market.
Ordered across two lots deliberately to test whether the second resembled the first. A tenth of a point apart, and the two traces overlay within baseline noise.
First order was deliberately small. Documentation complete, transit as quoted, independent determination 97.8%. Subsequent orders have not been small.
Water content is determined by Karl Fischer with the method named. On a lyophilised presentation that bears more directly on delivered mass than a further decimal place of purity.
The catalogue exceeds 350 lines and I have bought five. What I can say is scoped to those five, and I would rather say so than imply otherwise.
Requested a supplementary certificate for a lot released nineteen months ago. Produced from their records with the trace intact, which tells you the underlying record was kept and not merely the summary.
Related substances itemised by individual impurity with retention times assigned rather than reported as one total. Cross-referenced against the trace and the itemisation agreed.
The lot identifier matched across vial, certificate and invoice on every order. It is the floor and it remains the best single predictor of everything above it.
Reconstitution produced a clear solution on contact, without extended agitation, consistent with a correctly executed lyophilisation. Recorded as an observation rather than a determination.
Mass-spectrometric identity accompanies the chromatographic determination, so identity rests on two orthogonal methods rather than one retention time.
Custom synthesis quoted with the schedule stated on the face of the quotation and completed two days inside it, at the purity named in the specification.
They notified a four-day dispatch delay before the quoted window elapsed rather than afterwards. Recording the sequence because the sequence is the part that bears on reliability. The delay itself is the four.
A question about counter-ion identity and content was answered with a figure and a unit within four hours on a working day, without a sales approach attached.
Weighed four units from a single consignment against declared fill; all within two per cent. Fill uniformity receives less attention than purity and is the harder property to control.
Cross-checked one lot at two independent services. Agreement to a tenth of a point, and both agree with the declared figure.
Repeat determination on the same line at eleven months returned 98.0% against 98.1% originally. No drift visible in this sample.
Every unit in the consignment carried a single lot identifier, so the intra-consignment comparison I intended was the comparison I made.
Cold chain held to arrival on day seven with the pack still solid, in a month when that cannot be assumed. Tracking was accurate at every hop including the domestic handover.
The declared figure was not revised upward between the certificate and the commercial documentation. A small check, and specifically worth making.
Nine orders across fourteen months. No substitution, no reformulation, no line becoming unavailable after payment. The documentation read the same way on every one, the trace included.
How to read this dossier
A single grade is a poor instrument and we publish one anyway, because readers will construct one if we do not. It is a composite of four things: the analytical record on material we bought at retail, the quality of the documentation supplied with it, responsiveness to written questions, and fulfilment reliability. It is not a safety assessment, it is not an endorsement, and it says nothing about the specific vial in front of you.
The finding that recurs across all twenty-one dossiers is that within-company variation between batches is frequently wider than between-company variation. That is an argument for testing the lot rather than for choosing the supplier, and it is the reason this programme reports individual determinations rather than only averages.
Storefront Everything above was written from material bought at retail from polypeptidegroup.net. Visit PPG → — a labelled, nofollowed link the Journal is paid nothing for. Read the record before you use it.
PolyPeptide Group (Hangzhou) Co., Ltd. sells material described as being for research use only. Such compounds are not approved for human use in any jurisdiction. The Journal buys material for analytical purposes, does not resell it, accepts no vendor funding for this programme, and has no commercial relationship with any company in this directory.