Janoshik Testing: What Researchers Need to Know About the Most Referenced Peptide Lab

You have seen the name on dozens of COAs. Vendors paste it on product pages like a seal of approval. But how much do you actually know about the lab behind Janoshik testing?

Prague-based Janoshik Analytical was founded by Peter Magic around 2012–2013. Magic, a former amateur Slovak weightlifter and self-described med school dropout, started the operation as a “beer money” project to help bodybuilding friends verify compound quality. It grew into a full laboratory. The name derives from Juraj Janosik, a Slovak folk hero colloquially known as the “Slovak Robin Hood.” The company formally registered as Janoshik s.r.o. in October 2022, employs roughly 30 staff, and ran 3,050 GLP-1 peptide tests in 2024 alone. The leadership team includes Jakub Dobrik (Managing Director and CFO) and Edita Prokesova (Chief Scientific Officer). Magic maintains total abstinence from peptides and steroids personally, a detail he cites as protecting his legal and professional integrity.

This guide covers their methods, how to submit samples, how to verify (or catch faked) COAs, pricing, and the limitations every researcher should understand before treating a Janoshik report as gospel. For background on how we evaluate COAs across all labs, see our COA verification methodology.

What Janoshik Tests and How

Janoshik processed 3,050 GLP-1 samples in 2024, up from 650 in 2023. That 4.7x increase in one year was driven almost entirely by semaglutide and tirzepatide demand. The lab now runs roughly 100 peptide tests daily. Peptides account for 70–80% of total volume, a sharp pivot from steroid-testing origins. Reference standards follow EU Pharmacopoeia specifications.

The core analytical toolkit:

• HPLC-UV (High-Performance Liquid Chromatography with UV detection at 214–220 nm). The workhorse method. It measures purity as the percentage of the target peak area versus total UV-absorbing peak area. A 98.5% HPLC purity means 98.5% of what the UV detector sees is your target compound.
• LC-MS (Liquid Chromatography-Mass Spectrometry). Confirms identity by molecular weight. This matters because a peptide with a single amino acid substitution can show 99% HPLC purity while being a completely different compound.
• GC-MS (Gas Chromatography-Mass Spectrometry). Used for structural and contamination analysis, particularly for steroids and SARMs. The $170 GCMS/LCMS screening examines what comprises the remaining impurity fraction.
• LAL endotoxin testing. Results reported in EU/mL. Endotoxins are not live bacteria but bacterial cell wall fragments that can trigger immune reactions and fever. A clean HPLC result means nothing if the product causes pyrogen reactions.
• TAMC/TYMC sterility testing. Total Aerobic Microbial Count and Total Yeast and Mold Count detect live microbial contamination. Standard USP sterility panels.
• ICP-MS heavy metals analysis. Screens arsenic, cadmium, lead, and mercury at parts-per-billion levels. Peter Magic has stated he has found zero cases of heavy metal contamination in tested peptides and calls this test “useless and overrated” for the compound class.
• CHNS elemental analysis. Measures carbon, hydrogen, nitrogen, and sulfur content for mass reporting. Available on request.

One critical nuance: HPLC purity is not absolute peptide content. A 99% pure result means 99% of the UV-absorbing material is your target peptide. It does not detect water, salts, or non-chromophore contaminants. A vial reading 99% pure can contain only 70–85% net peptide content due to residual moisture, counter-ions (TFA, acetate), and atmospheric water absorbed during lyophilization.

The 2024 Janoshik testing data tells the rest of the story. 43% of peptides tested failed to meet label purity claims. Lower-tier vendors showed actual purities of 71–91% despite claiming 99%+. Some products contained entirely wrong compounds. In 2025, approximately 23% of retatrutide samples contained exendin-4 analogs instead of authentic retatrutide. For more on what purity actually means, see our peptide purity guide.

How to Submit a Sample to Janoshik

Submitting a sample for Janoshik testing requires international shipping to Prague. Budget one to two weeks for transit from the US. Here is the full process.

Step 1: Select your test. Visit janoshik.com and choose from the catalog. The Common GLP-1 Blind Test ($300) covers semaglutide, tirzepatide, and retatrutide identification plus purity and mass measurement. For unlisted compounds, contact the lab directly. The detection limit sits below 1/20th of the usual dosage per vial.

Step 2: Complete the order form and pay. Accepted payment methods include bank transfer (USD, EUR, CZK), Bitcoin, USDT ERC20, and Revolut. Cryptocurrency is accepted for those who prefer transaction privacy.

Step 3: Ship your sample to Prague. Minimum requirements for GLP-1 testing: one unopened lyophilized vial or 30mg of raw API powder in a sealed glass vial. Use tracked international shipping and include your order number with the package. US-to-Prague shipping runs approximately $50–75.

Step 4: Submit your tracking number via the order confirmation page.

Step 5: Receive results. Reports arrive via email and your customer account portal. Average turnaround is 96 hours from receipt, with a guaranteed maximum of 21 days (full refund plus free testing if exceeded). Community reports confirm 2–5 days for most tests.

Blind testing protocol. If you want unbiased results, do not identify the vendor on your submission. Use an alias shipping address and label only with the compound name. Ship from an address the vendor does not know. The point of blind testing is that the lab analyzes the compound without knowing who made it, removing any potential for vendor-relationship bias.

Rush processing doubles the base fee but cuts turnaround roughly in half.

Public vs. private results. All results are private by default. Publishing to the public.janoshik.com database costs an additional $70. This matters because the public database only contains results someone chose to publish. It is inherently cherry-picked. Vendors do not pay $70 to broadcast failures.

Batch shipping tip. If you are testing multiple vials, ship them together. You pay per test, but you only pay international postage once. The contact form also lists a “We want to test as a group” option, enabling community members to split shipping costs across multiple samples in one package.

How to Verify a Janoshik COA

A COA with Janoshik's name on it does not mean Janoshik tested that batch. Vendors have been caught doctoring real COAs, stripping verification codes, and attributing tests for one product to an entirely different one. Verification takes under a minute.

The verification system. Every authentic Janoshik COA contains two unique identifiers: a Task Number (top of document) and a Unique Key (bottom, case-sensitive). Enter both at public.janoshik.com to confirm the report is real and unaltered. A QR code on the COA links to the same verification page. Community guidance holds that it is rare for an altered test report to still include a valid QR code.

What verification catches. Altered COAs will not match the database. Removed or changed QR codes produce no match. A valid-looking Task Number paired with a wrong Unique Key will fail. The system confirms both identity and integrity of the original report.

Documented forgery cases. A vendor called Modern Peptides posted a Janoshik COA for a NAD+ product with the verification key and QR code removed. When investigated, the test number actually corresponded to QSC bacteriostatic water. The vendor had taken a real COA and pasted different product information onto it.

In a separate case, a vendor called ZLZ posted a COA where initial verification returned nothing. Forum investigation found a valid test existed, but the vendor had not provided the correct verification key, suggesting the key was stripped or swapped. The vendor refused to address the discrepancy and blocked the buyer on WhatsApp. Both cases follow the same pattern: real Janoshik test data repurposed to validate a different product.

Red flags on any COA:

• Missing or removed QR code or verification key
• Blurry scans (obscuring altered text)
• Dates that predate the vendor's existence
• Suspiciously round numbers across all metrics
• PDF metadata showing editing software (Photoshop, Illustrator)

The fundamental limitation of Janoshik testing. Even a fully verified, authentic COA only proves that one specific sample passed testing. It does not guarantee every vial in the batch is identical. Vendors test one vial and apply the results to their entire inventory. For more on evaluating COAs across all labs, see our full methodology and scoring framework.

Pricing and Turnaround

Turnaround: 96 hours average from sample receipt. The Common GLP-1 test specifically averages 5 days. Rush cuts it roughly in half. The guaranteed maximum is 21 days, backed by a refund-plus-free-test policy.

Shipping costs: $50–75 from the US to Prague, one-way. Group testing is available through the contact form, enabling community members to split shipping costs by sending multiple samples in one package.

Accepted payment: Bank transfer (USD, EUR, CZK), Bitcoin, USDT ERC20, and Revolut. Cryptocurrency is accepted for researchers who prefer transaction privacy.

Accuracy margins to know. The lab acknowledges a 5% error margin for peptide mass measurements, up to 10% for liquid suspensions, and 20% for HCG. Detection cutoffs range from 2mg (SARMs in pills) to 15mg/mL (oils). These margins matter when comparing results across labs or evaluating borderline results.

Context on cost. $300 for a GLP-1 test sounds steep until you consider what you are verifying. A 10mg vial of tirzepatide from a gray-market vendor costs $30–80. A 3-month supply runs $200–500. Spending $300 to confirm the first batch actually contains what the label says, at the purity claimed, is reasonable relative to the alternative: injecting an unverified compound. Test one batch from a new vendor. If results confirm identity, purity, and mass, you have a baseline for that supplier.

Limitations and Known Issues

Purity Percentage Is Not Net Peptide Content

This is the most misunderstood number in Janoshik testing reports. Peter Magic has stated directly that the mg figure on a typical peptide analysis is not the net peptide content. The reported mass includes counter-ions, residual solvents, and stabilizing fillers (typically mannitol) added during lyophilization.

What this means in practice: a 10mg vial testing at 98% purity could contain only 7–8.5mg of actual active peptide. The remaining mass is water, TFA salt, and other non-peptide material that HPLC does not detect.

Determining net peptide content (NPC) requires a separate quantitative test. Most vendor COAs skip this entirely. When a vendor claims “10mg at 99% purity,” that 99% refers to relative composition of UV-absorbing material. It says nothing about absolute quantity.

One counterpoint: many vials are overfilled 10–20% above label. Mass testing often reveals more content than labeled. But without NPC data, you cannot confirm how much of that mass is active peptide versus filler.

No ISO 17025 Accreditation

ISO/IEC 17025 is the international standard for testing laboratory competence. It requires documented management systems, external audits, proficiency testing participation, and technical competence verification.

Janoshik does not hold it. Their results cannot support regulatory submissions, clinical trials, or any pharmaceutical context.

Context matters, though. No gray-market testing lab holds ISO 17025 for these specific peptide assays. Not Chromate. Not Krause Analytical. Not PeptideTest.com. Not Freedom Diagnostics. The accreditation gap is industry-wide. Academic labs that do hold accreditation (Eurofins, SGS, Intertek) charge $200–$1,000+ per sample, serve pharmaceutical clients, and would not accept gray-market samples.

COAs also lack detailed methodology. They do not list which HPLC column, gradient program, or MS parameters the lab used. Raw chromatographic data requires additional payment to access. Cross-validation data provides partial confidence in lieu of formal accreditation, but “partial confidence” and “accredited” are not interchangeable terms.

February 2026 Data Breach

In February 2026, Janoshik experienced a data breach that exposed customer shipping information and database contents. Attackers attempted extortion.

The practical takeaway: use a dedicated email address and a shipping alias (PO box or mail drop) for any future submissions. Do not use your primary personal email or home address. The breach underscores a risk inherent to any online submission. Your testing history becomes a data liability.

Other Known Issues

Peter Magic acknowledged placing false credential information on the site, described as a “joke.” Unresolved allegations also exist of results issued on samples the lab had not received. The lab processes over 800 emails daily during peak periods, and the acknowledged error margin is 5% for peptide mass measurements (up to 10% for liquid suspensions, 20% for HCG).

The structural conflict is worth naming: vendors are significant paying customers of the lab they rely on for credibility. This does not prove bias, but the incentive structure exists. The lab's economic interest in maintaining its reputation partially mitigates this concern. A single proven case of vendor favoritism would damage Janoshik's core business model.

How Janoshik Compares to Other Testing Labs

The best evidence for any lab's accuracy comes from cross-validation, where multiple labs test identical samples independently. Janoshik testing has the deepest cross-validation dataset in the gray-market peptide space.

The retatrutide benchmark. In a community-organized cross-validation test on the same batch, Janoshik reported approximately 30mg across 9 vials. Chromate aligned at approximately 30mg. Krause Analytical reported 26mg on both tested vials, a full 15% lower. The Janoshik-Chromate agreement is strong evidence of measurement accuracy. The Krause discrepancy raises questions about systematic underestimation at that lab.

Mislabeling detection. When Coastal Peptides semaglutide samples actually contained cagrilintide, Janoshik correctly identified the substitution. Chromate initially missed it and later issued a corrected COA. Chromate issued three corrected COAs total in spring 2025 for misidentified compounds that Janoshik caught correctly. To their credit, Chromate corrected the records publicly.

Upstream recognition. Chinese peptide manufacturers specifically honor guarantee claims when backed by Janoshik results. This suggests the lab has penetrated the upstream supply chain as a trusted reference, not just the retail buyer community.

Longevity signal. Over a decade of consistent operation with an intact reputation in a gray-market context where most services either disappear or get exposed as fraudulent. That track record is itself evidence of reliability.

Comparison framework:

US-based labs offer the obvious advantage of domestic shipping (cheaper, faster, no customs risk). Janoshik's advantages are track record length, blind testing validation depth, and the forensic COA verification system.

Our recommendation for high-stakes testing: dual-lab confirmation. Send identical samples to two independent labs. Total cost runs $400–600 depending on compound type. When two labs agree on identity, purity, and mass, your confidence level increases substantially. When they disagree, that disagreement itself is valuable data. For vendor-level comparisons that factor in testing data, see our vendor ratings.

Frequently Asked Questions

Is Janoshik accredited?

No. Janoshik lacks ISO/IEC 17025 accreditation, and no external body audits their procedures. This is not unique to Janoshik. No gray-market peptide testing lab holds this accreditation. Cross-validation data with other labs shows consistent alignment on mass and identity, which provides practical (but not formal) confidence in results.

How long does testing take?

Average turnaround is 96 hours (about 4 business days) from sample receipt. The Common GLP-1 test specifically averages 5 days. Rush processing at 2x the base fee cuts turnaround roughly in half. The lab guarantees a maximum of 21 days with a full refund and complimentary retest if exceeded. International shipping adds 5–10 business days depending on your location.

Can vendors fake a Janoshik COA?

Yes, and some have been caught doing exactly that. Always verify using the Task Number and Unique Key at public.janoshik.com. If either identifier is missing or the QR code has been removed, treat the COA as unverified. Documented cases include vendors pasting Janoshik test numbers from unrelated products onto their own COAs.

What is the difference between purity and net peptide content?

Purity measures relative composition. If HPLC shows 99% purity, that means 99% of the UV-absorbing material is your target peptide. Net peptide content (NPC) measures absolute quantity. A 99% pure 10mg vial might contain only 7–8.5mg of actual peptide because the remaining mass is water, counter-ions, and lyophilization fillers that HPLC cannot detect. NPC requires a separate quantitative test that most vendor COAs do not include.

How much does testing cost?

The Common GLP-1 Blind Test (semaglutide, tirzepatide, retatrutide) costs $300. Steroid screening runs $120. SARM screening is $170. Rush processing adds 100% to any base fee. Publishing results to the public database costs an additional $70. Budget $50–75 for US-to-Prague shipping on top of the test fee.