Peptide Information Hub Purity · COA · Reconstitution · Storage · Safety · Everything Researchers Need to Know
Research peptides are short chains of amino acids (typically 2-50 residues) synthesized for in vitro laboratory research into biological signaling pathways. Unlike pharmaceutical compounds, research peptides are not FDA-approved drug products — they are supplied for laboratory investigation only. Quality research peptides are characterized by high HPLC purity (≥99%), independent mass spectrometry identity confirmation, and lyophilized (freeze-dried) formulation for storage stability.
Research peptides are short chains of amino acids (typically 2-50 residues) synthesized for in vitro laboratory research into biological signaling pathways. Unlike pharmaceutical compounds, research peptides are not FDA-approved drug products — they are supplied for laboratory investigation only. Quality research peptides are characterized by high HPLC purity (≥99%), independent mass spectrometry identity confirmation, and lyophilized (freeze-dried) formulation for storage stability.
Certificate of Analysis (COA) — What to Look For
A COA is the primary quality document for a research peptide batch. A trustworthy COA includes: HPLC purity percentage (≥99% for research grade), mass spectrometry molecular weight confirmation, batch/lot number, testing date, and the identity of the testing laboratory. The critical distinction: independent COA vs in-house COA. QSC uses Janoshik — an independent European analytical laboratory whose results are published at verify.janoshik.com. Anyone can verify QSC’s COA using only the batch code, without any trust in QSC.
HPLC Explained
HPLC (High-Performance Liquid Chromatography) separates the components of a peptide sample through a column and measures each component’s relative percentage by UV absorbance. The result is a purity percentage: what fraction of the sample is the target peptide vs. impurities. Research grade: ≥99% HPLC. The HPLC chromatogram should be included in the COA — not just a number. A COA showing only a purity number without the chromatogram graph cannot be verified.
Mass Spectrometry (MS) Explained
Mass spectrometry (MS) confirms the molecular weight of the compound matches the theoretical molecular weight of the target peptide. HPLC tells you purity percentage; MS tells you identity — that you have the correct compound at all. Both are required for a complete COA. A peptide showing 99% HPLC purity could theoretically be 99% of the wrong compound — MS identity confirmation catches this. QSC COAs include both HPLC and MS on every batch.
Lyophilization and Peptide Stability
Research peptides are supplied in lyophilized (freeze-dried) form — a white/off-white powder in a sealed vial. Lyophilization removes water content, extending shelf life to 2-3 years when stored properly. Lyophilized peptides should be stored at −20°C, protected from light, and kept dry. Most peptides are stable at 4°C (refrigerator) for up to 3-6 months if not reconstituted. Avoid repeated freeze-thaw cycles after reconstitution.
Frequently Asked Questions
What is research-grade peptide purity?
Research-grade peptides should have ≥99% HPLC purity. This means ≥99% of the measured sample is the target peptide, with impurities comprising ≤1%. Some research applications require ≥98% (standard grade) while others require ≥99% (high grade). QSC supplies all compounds at ≥99% HPLC purity verified by Janoshik independent laboratory. Research use only.
What is the difference between HPLC purity and net peptide content?
HPLC purity measures what fraction of the sample is the target peptide vs impurities. Net peptide content (NPC) measures what fraction of the vial’s total weight is actual peptide vs water content (residual moisture) and salt counterions (TFA is common). A peptide can show 99% HPLC purity but 70% net peptide content — the 30% difference is water and salts. NPC affects dosing calculations. QSC COAs include both measurements.
How do I reconstitute a research peptide?
Most research peptides are reconstituted with bacteriostatic water (BAC water — sterile water with 0.9% benzyl alcohol preservative) for multi-use vials, or sterile water for single-use. Add the diluent slowly down the side of the vial — do not inject directly onto the lyophilized cake. Swirl gently; do not shake or vortex, which can damage peptide bonds. Use the molecular weight and target concentration to calculate volume needed. Store reconstituted peptides at 4°C for up to 30 days or at −20°C for longer storage.
How should research peptides be stored?
Lyophilized (unreconstituted): −20°C, dark, dry — stable 2-3 years. Short-term lyophilized storage: 4°C, dark — stable 3-6 months. Reconstituted peptides: 4°C for up to 30 days. Reconstituted long-term: −20°C, aliquot to avoid freeze-thaw cycles. Fragile peptides (GHK-Cu, oxytocin, some GLP-1 class): −80°C preferred for long-term. All QSC products include storage guidance on the product page.
Research Use Only: All QSC products sold strictly for in vitro laboratory research. Not for human or veterinary use. Information on this page is educational and does not constitute medical advice.
