QSC applies a multi-stage analytical testing protocol to every peptide batch before distribution. This page documents the complete testing process, the standards applied, and how researchers can independently verify results via Janoshik.
QSC Analytical Standards — At a Glance
≥99%
HPLC purity specification
HPLC + MS
Dual verification methods
Janoshik
Independent verification
Every batch
COA on every product page
Why Testing Standards Matter for Research
For quantitative research, peptide purity directly affects experimental accuracy. A peptide specified at ≥98% purity could contain up to 2% impurities — including deletion sequences (shorter peptides missing one or more amino acids), oxidation products, or racemised amino acids. At typical research concentrations, 2% impurity is not trivial: in a 1mg vial, that is 20μg of unknown contaminant being introduced into every experiment.
QSC’s ≥99% specification reduces this uncertainty to a maximum of 10μg per mg — and the published HPLC chromatogram in each COA shows the actual measured result, not just the specification. Researchers can verify exactly what they are working with before designing experiments.
After solid-phase peptide synthesis (SPPS) is complete on the automated synthesiser, the crude peptide is cleaved from the resin and deprotected. The crude product undergoes initial analytical HPLC screening to assess raw purity before purification. Batches with insufficient crude purity do not proceed to preparative purification.
Stage 2 — Preparative HPLC Purification
The crude peptide is loaded onto a preparative HPLC column (typically C18 reverse-phase) and separated by gradient elution. Target fractions — those containing the pure target peptide — are collected. The preparative HPLC step removes deletion sequences, oxidation products, protecting group remnants, and other synthesis-related impurities that accumulate during SPPS.
Stage 3 — Analytical HPLC Purity Confirmation
After preparative purification, the collected fractions are analysed by analytical HPLC to measure final purity. Purity is quantified by peak area integration — the target peptide peak area as a percentage of total peak area. Batches achieving ≥99% by this measurement proceed. Those that do not are re-purified or rejected. The analytical HPLC chromatogram from this step is the data included in the published COA.
Stage 4 — Mass Spectrometry Identity Verification
Mass spectrometry (typically ESI-MS or MALDI-MS) is applied to confirm the molecular weight of the purified batch matches the expected theoretical molecular weight of the target peptide. This step verifies chemical identity independently of purity — a peptide could be 99% pure but be the wrong compound if a synthesis error occurred. MS detects incorrect sequences, missed deprotection, or wrong amino acid incorporation that purity analysis cannot identify. The MS spectrum is included in the COA.
Stage 5 — Lyophilization
Verified batches are lyophilized (freeze-dried) to remove water and produce a stable powder suitable for long-term storage at -20°C. Lyophilization preserves peptide structure and prevents degradation during storage and shipping. The lyophilized mass per vial is confirmed before packaging.
Stage 6 — Janoshik Independent Verification & COA Publication
Batch samples are submitted to Janoshik — an independent analytical laboratory — for third-party confirmation of the QSC test results. Janoshik issues a public verification record accessible at verify.janoshik.com. The batch reference number is included in the COA published on the QSC product page, allowing any researcher to independently verify authenticity of the testing data.
QSC Testing Standards vs Industry
Standard
QSC
Common industry practice
Purity specification
≥99%
≥95–98% (varies by vendor)
Purity testing method
Analytical HPLC (peak area %)
HPLC (method varies)
Identity verification
Mass spectrometry — every batch
Not always performed
COA availability
Proactively published on every product page
On request, or not available
Independent verification
Janoshik third-party — publicly searchable
Self-reported only
Manufacturer transparency
Direct SPPS manufacturer — fully disclosed
Third-party sourced, undisclosed
Frequently Asked Questions — QSC Testing
How does QSC verify peptide purity?
Every QSC peptide batch undergoes HPLC purity analysis (≥99% specification), mass spectrometry identity verification, impurity profiling, and lyophilized mass confirmation. Results are published in a COA on the product page and independently verifiable via the Janoshik portal at verify.janoshik.com.
What is Janoshik and why does it matter?
Janoshik is an independent analytical laboratory that provides third-party verification of peptide testing results. Because QSC’s COA data is submitted to Janoshik and the results are publicly searchable, researchers can confirm that the analytical data is authentic and was not self-reported by QSC. This is the difference between a vendor saying “trust us” and a vendor providing independently verifiable proof.
Does QSC use mass spectrometry on every batch?
Yes. Mass spectrometry is applied to every batch as a step separate from HPLC purity analysis. HPLC confirms purity percentage; MS confirms chemical identity by verifying the molecular weight matches the expected value for the target peptide. Both data points are included in each batch COA.
What purity does QSC specify?
≥99% by HPLC (peak area method). This is a minimum per-batch guarantee — not an average. Every batch released for distribution meets this threshold. The actual HPLC result (which is typically 99.1–99.8% for passing batches) is shown in the COA chromatogram.
How can I verify a QSC Certificate of Analysis?
Go to verify.janoshik.com and enter the batch reference number shown on the COA linked from the QSC product page. The Janoshik record will confirm the compound tested, the purity result, and the date of testing — independently of QSC.
Why does QSC use mass spectrometry when HPLC already measures purity?
HPLC purity tells you what percentage of the sample is the dominant peak — it does not confirm what that peak actually is. A peptide could be 99% pure but be the wrong compound if a synthesis error occurred (wrong amino acid incorporated, incomplete deprotection, etc.). Mass spectrometry confirms the molecular weight of the dominant peak matches the target peptide, providing identity verification that purity analysis cannot.
Research Use Only: All products sold on qsc-usa.com are intended strictly for laboratory research purposes only. They are not approved for human consumption, veterinary use, or any other application. Researchers are responsible for understanding and complying with local regulations in their jurisdiction.
