Retatrutide Testing: HPLC Purity and Mass Spectrometry Guide

Retatrutide Testing Overview

Retatrutide is a triple agonist targeting GLP-1, GIP, and glucagon receptors with a molecular weight of approximately 4,733.05 Da. As an investigational peptide not yet approved for clinical use, testing is particularly important because there is no regulatory oversight of retatrutide sold for research purposes. Independent HPLC and LC-MS testing provides the only reliable quality verification.

HPLC Purity Standards for Retatrutide

Retatrutide should be analyzed by reverse-phase HPLC on a C18 or C8 column with UV detection at 214 nm. The purity percentage is derived from the main peak area divided by total peak area.

• Acceptable purity: ≥98%
• Premium grade: ≥99%
• Watch for: Broad peaks (indicate aggregation), multiple peaks near the main peak (truncation products), or a main peak below 90% (significant contamination)

LC-MS Identity Confirmation

The theoretical molecular weight of retatrutide is 4,733.05 Da. LC-MS analysis should show this mass within ±0.1%. Common substitutes include tirzepatide (4,813.52 Da) and semaglutide (4,113.58 Da), both of which are detectable by their different molecular weights.

Retatrutide Stability and Degradation

Retatrutide is sensitive to temperature and pH. Improper storage leads to degradation products that appear as additional peaks in HPLC. Key stability factors:

• Temperature: Store at -20°C or below. Room temperature storage for more than 48 hours causes measurable degradation.
• Freeze-thaw cycles: Each cycle degrades 1-2% of the peptide. Limit to 2-3 cycles.
• Reconstitution: Use sterile bacteriostatic water. Acidic solvents can accelerate degradation.
• Light exposure: UV light damages the peptide bonds. Store in amber vials or dark conditions.

Interpreting a Retatrutide COA

A legitimate retatrutide COA should contain HPLC purity data, LC-MS identity confirmation, fill weight, and storage recommendations. Be cautious of COAs that show only a purity percentage without a chromatogram — these can be fabricated. Always verify the testing laboratory exists and is accredited.