How every lot gets made

Sourcing & provenance

X Factor is not a manufacturer and does not synthesize peptides. Finished research material is sourced from vetted suppliers with documented provenance, and every lot arrives with the supplier's per-lot certificate of analysis.

Provenance: US-based supply partners. Each lot ships with the supplier's per-lot certificate of analysis (HPLC purity + LC-MS identity).

Reversed-phase HPLC purification

Crude peptide is loaded onto a C18 prep column and eluted with a water/acetonitrile gradient containing 0.1% TFA. Fractions are collected by UV detection at 220 nm. Only fractions meeting ≥99% area purity are pooled and re-lyophilized to powder.

Bench mark: prep C18, 220 nm UV, mass-directed fractionation when available.

Mass spectrometry confirmation

Purified material is checked by ESI-MS or MALDI-TOF. The supplier confirms the observed monoisotopic mass matches the calculated mass within ±0.5 Da, and this result is recorded on the lot certificate; a disagreement triggers a hold and re-run before release.

Analytical HPLC for the lot certificate

A fresh analytical RP-HPLC injection is run on the finished, lyophilized material. This is the trace that gets archived as the lot COA. Integrated peak areas, retention times, gradient method, column part number, and operator initials all go on the certificate.

Released minimum: ≥99% main-peak area purity. Anything below: hold or destroy.

Endotoxin and bioburden (where applicable)

For SKUs intended for cell-culture or animal-research applications, the supplier runs a LAL endotoxin assay and reports the EU/mg result on the lot certificate. Bioburden plates may be included for institutional buyer requests.

Note: these are research-grade limits, not pharmacopeial limits. Read the COA carefully.

Vial fill, label print, lot assignment

Lyophilized material is dispensed under HEPA-filtered laminar flow into 2 mL or 5 mL flint borosilicate vials, stoppered, and crimped with a colored aluminum seal (brand red for catalog SKUs). Labels print with the SKU, lot number, fill weight, manufacture date, and storage instruction. Each vial gets a tamper-evident sticker.

QC release

Intake check: each incoming lot is reconciled against its supplier certificate of analysis before release — lot number, purity, and identity must match. Released lots move to the cold-room (−20°C) and are picked from there when an order ships. Lots that don't reconcile stay quarantined and cannot be picked by the WMS.

Order pack and ship

Each picked vial is packed with insulation and a freeze-pack appropriate to the destination zip-code transit time. The lot COA is printed and packed inside. Tracking emails go to the customer with a link to the public COA page for that lot at /coa/.

Retention and stability

The supplier's per-lot certificate of analysis is retained and available on request. Quality concerns are reconciled against that documentation with the supplier.