Quality standard
No certificate, no sale.
Every lot is tested by HPLC and mass spectrometry before it can go on sale. A lot below our 99.0% release minimum, more than 1.0 Da off the mass its sequence implies, or without its certificate on file can’t be listed or sold: the store’s own software refuses it.
Simulated lot
Release check
The six checks the store runs before a lot can go on sale. Change one to see what it does.
Release minimum99.0%HPLC purity, at or above
Publishable. Every check passes: it can be listed and sold.
Sample records (lot numbers starting DS-SPEC-) never pass in the live store.
How a lot is tested
Two instruments, one sequence.
Purity is the main peak’s share of the HPLC signal. Identity is the measured mass, next to the mass the sequence implies. Move along a trace to read it the way the lab does.
How much of the signal is the main peak
Reversed-phase HPLC runs the sample through a column while the solvent shifts from water toward acetonitrile. Each component leaves at its own time, and a UV detector at 220 nm, where the peptide bond absorbs, draws it as a peak.
- Separation
- Reversed phase, solvent gradient
- Detection
- UV absorbance, 220 nm
- Result
- Main-peak area ÷ total area
Passes whenThe main peak is at least 99.0% of the total peak area.
What HPLC purity means, and doesn’tWhether it has the right mass
Electrospray ionization adds protons, so one peptide shows up at several charge states, each at its own m/z. Deconvoluted, they give a single mass, which is compared with the mass calculated from the sequence.
- Ionization
- Electrospray, positive mode
- Reads
- m/z of each charge state
- Result
- Observed vs. calculated mass
Passes whenThe observed mass is within ±1.0 Da of the sequence’s calculated mass.
Mass spectrometry and identityWhat the mass is checked against
Every listing publishes its full sequence, and the calculated mass comes from it. A missing or extra residue lands far outside the ±1.0 Da tolerance, but a change under it can pass, such as deamidation (+0.98 Da), and isomers weigh the same (see below).
- Residues
- 39
- Formula
- C221H342N46O68
- Average mass
- 4731.348 Da
Used forThe theoretical mass on every certificate, and the identity check against it.
Explore it in Sequence StudioRetatrutide
Example values- Main peak
- 17.72 min
- HPLC purity
- 99.41%
- Other peaks
- 0.59% · 5 peaks
Illustration from this lot’s numbers
Turn on JavaScript to read the chromatogram, the mass spectrum and the sequence.
Move along the trace, or focus it and use the arrow keys. Point at a row to find its peak.
| Peak | Time, min | Area, % | Type |
|---|---|---|---|
| 1 | 15.75 | 0.16 | Impurity |
| 2 | 16.32 | 0.08 | Impurity |
| 3 | 16.76 | 0.18 | Impurity |
| 4 | 17.21 | 0.12 | Impurity |
| 5 | 17.72 | 99.41 | Main peak |
| 6 | 19.31 | 0.05 | Impurity |
Example values: a lot simulated from this peptide’s sequence, not a test result. When a published lot is current, its record and its certificate are shown here in their place.
Certificate of analysis
What each line means.
Every published lot has one, linked from its product page and from Verify. Each numbered note explains a line to look for on it.
Certificate of analysis
Retatrutide
| Product | Retatrutide |
|---|---|
| Sequence | Y |
| Modifications | Lys17: C20 diacid–γGlu–AEEAC-terminal amide |
| Lot number | Recorded per lot |
| Theoretical massAverage, from the sequence | 4731.348 Da |
| Observed massESI-MS, deconvoluted | 4731.335 Da |
| PurityRP-HPLC, UV 220 nm | 99.41% |
| Method | RP-HPLC (UV 220 nm)ESI-MS |
| Test date | Recorded per lot |
| Laboratory | Named per lot |
For laboratory research use only. Not for human or veterinary use.
-
The compound the lab tested, written out in full with any modifications. It must match the listing you ordered.
-
Ties the document to one batch of vials. It must match your label exactly, and it opens its record on Verify.
-
Calculated from the sequence: the same figure the product page shows, and what identity is checked against.
-
What mass spectrometry measured: the identity test. The store won’t publish a lot whose observed mass is more than 1.0 Da from the theoretical mass.
-
The main peak’s share of the total peak area. The store won’t publish a lot below the 99.0% release minimum.
-
How each number was measured. A purity figure without its method and wavelength is weaker evidence.
-
When the lot was tested, and who ran the analysis.
What we don’t claim
The limits of the evidence.
A certificate is evidence about one lot, measured two ways. We say what it measured, and nothing beyond it.
-
No claims of “highest purity”
We publish the minimum we enforce and each lot’s measured result. We don’t rank ourselves against anyone, or call any lot the best.
-
No medical use
These are research compounds: not drugs, foods or supplements, and not for human or veterinary use. Nothing here is medical advice of any kind.
-
Not sterility or endotoxin
HPLC and mass spectrometry don’t test for either. When a certificate covers them, they’re separate lines.
-
Not peptide content
Purity is the main peak’s share of the signal, not the peptide’s share of the powder’s weight. Water and counter-ions weigh something too.
-
Not every difference
Mass alone can’t tell leucine from isoleucine or a D-residue from its L form, and a change under the ±1.0 Da tolerance can pass it, such as deamidation or a free acid where the sequence has an amide (+0.98 Da each). That is one reason purity and identity are measured separately.
-
Not your results
A certificate describes the lot as it was tested. It isn’t a promise about any experiment or outcome.
Your vial
Check the lot in your hand.
The lot number on the label opens the record we published for it: the same numbers, and the same certificate.
Packaging and storage
Supplied as lyophilized powder in sealed glass vials with crimped caps, each labelled with its lot number. Lyophilized peptides generally tolerate the days in transit. On arrival, store them as the lot’s documentation says; most are kept at −20 °C, dry and away from light.
If something looks wrong
If a lot number doesn’t verify, a seal is broken, or a vial doesn’t match its listing, tell us with your order number and a photo. We’ll investigate and make it right under our returns policy.