Each stage has documented in-process controls and a downstream-quality gate. Failed controls trigger investigation and rework before the batch advances; nothing skips forward on assumption.
01
Raw material qualification
Every incoming Fmoc-protected amino acid, coupling reagent, and process solvent is qualified against pharmacopeia specifications before release to the synthesis floor. Per-lot identity, purity, and water content are confirmed at receipt; out-of-spec material is quarantined and returned to the supplier with non-conformance documentation.
02
Solid-phase synthesis (SPPS)
Fmoc-strategy SPPS on multiple parallel reactor lines, scale-graded from research-batch (10-100 g) through pilot (1-10 kg) to commercial production. Synthesis cycle yield is monitored at every coupling-deprotection iteration; failed-coupling cycles trigger re-coupling before the next residue addition.
03
Crude cleavage & precipitation
TFA-based cleavage from the resin under controlled-temperature conditions appropriate to the side-chain protection scheme. Crude peptide is precipitated into cold ether, washed, and held under nitrogen prior to purification. The crude-cleavage step is a critical-quality checkpoint for peptides with oxidation-sensitive residues.
04
Reverse-phase HPLC purification
Preparative RP-HPLC at column scales from analytical (4.6 mm internal diameter) through semi-preparative (50 mm) to production (300+ mm). Purification cycles target ≥99.0% area-purity on the analytical re-injection. Closely-eluting truncation and deletion impurities are cut against measured chromatographic resolution rather than blind retention-window assumption.
05
Counter-ion exchange
TFA-salt material from purification is exchanged to the target counter-ion (acetate by default) by either repeated lyophilization from dilute acetate buffer or ion-exchange chromatography. Counter-ion content is quantified on the released batch, acetate-salt material typically reports 4-12% counter-ion by mass.
06
Lyophilization
Freeze-drying under vacuum with controlled shelf-temperature ramp and ice-condenser tracking. Lyophilization cycle parameters are optimized per peptide class, short hydrophilic peptides versus longer lipidated peptides versus copper-coordinated peptides each have different optimal cycles. Residual moisture is measured post-lyophilization by Karl Fischer.
07
ISO 7/8 sterile vial fill
Sterile-filtration through 0.22 µm filters into sterile holding tank, followed by aliquot fill into pre-sterilized vials under ISO 7/8 cleanroom conditions. Vial-fill weight is verified gravimetrically per-vial during the session; container-closure integrity (CCI) is tested on a sampling basis per the release protocol.
08
Analytical release testing
Released-batch QC covers HPLC purity (target ≥99.0% area), ESI mass spec confirming molecular weight within 0.5 Da of theoretical, water content by Karl Fischer, counter-ion content, and (for >15-residue peptides) LC-MS/MS sequence verification. Add-on tests on request: LAL endotoxin per USP <85>, microbial limits per USP <61>/<62>, stability data on the specific lot.
09
Cold-chain shipment
Outbound packaging is selected for the destination, transit time, and agreed temperature range. Temperature logging can be included when specified for the route; the resulting record then accompanies the shipment documentation at receipt.
