Peptide Lab Testing: Janoshik Purity Results for Retatrutide, Tirzepatide & GHK-Cu

When you buy research peptides, the label is only half the story. What matters is whether the material inside matches it — the right compound, at high purity, from a traceable batch. That’s why the Apex research pens we stock are sent to Janoshik Analytical, an independent third-party laboratory, and why we publish the results in full.

This post collects every current report for our range, explains what each result means, and shows you how to verify the reports yourself.

All results at a glance

Each report number links to the original report on Janoshik’s verification site.

Who are Janoshik?

Janoshik Analytical is an independent testing laboratory widely used across the research peptide market. Samples are sent to them directly, they run the requested analysis, and each finished report is published on their own verification site with a unique key — so results can’t be quietly edited by the supplier.

Retaklik (retatrutide)

Retaklik has the most complete testing record in our range, covering all three strengths and two separate 40mg batches.

• 20mg — batch 001/26: retatrutide 7.37 mg/ml, purity 99.071%. Janoshik noted the sample was tested twice. Analysed 4 February 2026.
• 40mg — batch 002/26: retatrutide 12.73 mg/ml, purity 99.278%. Analysed 4 February 2026.
• 40mg — batch 6/2026: tested blind against semaglutide, tirzepatide and retatrutide. Identified as retatrutide at 17.34 mg/ml, purity 99.029%. Analysed 24 July 2026.
• 40mg — batch 6/2026 sterility: TAMC PASS, TYMC PASS. Analysed 4 August 2026.
• 60mg — batch 003/26: retatrutide 27.72 mg/ml, purity 99.452%. Analysed 4 February 2026.

View the Retaklik Research Kit →

Klikjaro (tirzepatide)

Both Klikjaro strengths were submitted as blind tests, meaning Janoshik screened each sample against semaglutide, tirzepatide and retatrutide without being told which one to expect.

• 40mg — batch 07/2026: identified as tirzepatide at 17.88 mg/ml, purity 99.304%. Analysed 31 August 2026.
• 60mg — batch 07/2026: identified as tirzepatide at 25.93 mg/ml, purity 99.408%. Analysed 31 August 2026.

View the Klikjaro Research Kit →

Klik-GHK (GHK-Cu)

• 100mg — batch 07/2026: GHK-Cu 39.18 mg/ml (GHK content 32.54 mg/ml, copper content 6.64 mg/ml), purity 99.770% — the highest purity result in our range. Analysed 31 August 2026.

View the Klik-GHK Research Kit →

How to read a Janoshik report

Sample, manufacturer and batch

The top of each report shows what was submitted and which production batch it came from. The batch number is what links a report to the product in your hands.

Tests requested

• Assessment of a peptide pen — identifies the compound in a pre-filled pen and measures its concentration and purity.
• Blind test — the lab isn’t told which compound to expect and screens against several (here semaglutide, tirzepatide and retatrutide). A correct identification confirms the product is what the label says.
• Sterility testing (TAMC + TYMC) — a microbiological check. TAMC is the Total Aerobic Microbial Count; TYMC is the Total Yeast and Mould Count. A pass means the sample met the lab’s acceptance criteria for both.

Concentration (mg/ml)

The amount of the compound measured per millilitre of solution in the pen. This confirms the compound is present in a meaningful quantity, not just detectable.

Purity (%)

The proportion of the target compound relative to other peptide-related material detected. Every result above is over 99%.

Lab comments

Some reports include notes from the lab. On two reports, Janoshik noted that “the peak corresponding to the cresol was not counted among impurities.” Cresol is a preservative commonly used in pre-filled pen solutions, so it is an intended ingredient rather than a contaminant. Another report notes that the purity assessment covers peptide peaks only.

How to verify a report yourself

1. Click any report number in the table above to open it on Janoshik’s own site, verify.janoshik.com.
2. Or go to janoshik.com/verify and enter the unique key printed at the bottom of the report.
3. Check that the sample name, batch number and results match what we’ve published.

Because reports are hosted by the lab rather than by us, you can always confirm they’re genuine.

What about products not listed?

Reports above cover Retaklik, Klikjaro and Klik-GHK. For Retaklik 2.0 or Wolverineklik batch documentation, contact us before ordering and we’ll send what’s available. We add new reports as further batches are tested.

Order tested research products

UK orders ship with Royal Mail Special Delivery Guaranteed by 1pm — order before 4pm on working days for same-day dispatch. New customers can use code FIRST10 for 10% off their first order, and free shipping applies on orders over £200.

New to the pen format? Read Apex Research Pens vs Traditional Peptide Vials.

Research use only

For laboratory research purposes only. Products are not intended for human or veterinary use, diagnosis, treatment, cure, or prevention of any disease. Purchasers are responsible for ensuring compliance with all applicable laws and regulations.