Research Use Only. The information below is intended for qualified laboratory personnel handling research peptides in controlled environments. Products referenced are not medications and are not for human or veterinary use.

For foundational context, see Peptide Purity, Storage Best Practices, and Peptide Synthesis.

Overview

Retatrutide is an investigational, multi-receptor peptide. Like other lab peptides, optimal reconstitution hinges on purity, solvent selection, pH control, and cold-chain discipline. The goal is to achieve a clear, particulate-free working solution at a validated concentration—aliquoted to prevent freeze–thaw degradation and documented for traceability.

Required Materials

• Lyophilized retatrutide peptide (verified CoA with HPLC/MS)
• Sterile diluent(s): nuclease-free water for injection (WFI), 0.9% NaCl, or acidified aqueous (e.g., 0.1% acetic acid); optional minimal % DMSO for hydrophobic sequences
• Sterile low-protein-binding microtubes and pipette tips
• Optional: 0.22 µm sterile filter (low protein-binding)
• Ice bucket/cold rack; calibrated micropipettes
• Amber vials or foil wrap (light protection)
• Labeling supplies for lot, concentration, date, and storage temp

Solvent Selection & Decision Path

1. Start simple: Attempt reconstitution with sterile WFI or 0.9% NaCl at cold temperature (2–8 °C).
2. If partial dissolution: Add a small proportion of acidified aqueous (e.g., 0.1% acetic acid) to promote solubility while maintaining near-physiologic ionic strength for assays.
3. If still insoluble (hydrophobic domains): Pre-wet with a minimal volume of DMSO (e.g., 2–5% final), then stepwise dilute with your aqueous buffer to target concentration. Avoid high DMSO (>10–20%) unless assay-validated.
4. Protect sensitive residues: For Met/Cys-rich sequences, minimize oxygen exposure, keep cold, and consider inert gas overlay during aliquoting.

Tip: Keep pH mildly acidic (≈5–6) when feasible to mitigate deamidation; avoid strong base unless your protocol requires it.

Step-by-Step Reconstitution Protocol

1. Equilibrate & Inspect: Bring the vial to 2–8 °C to avoid condensation ingress. Confirm the lyophilized cake is intact and the cap seal uncompromised.
2. Calculate Target Volume: Decide your working concentration (e.g., 1 mg/mL or 100 µM). Use the peptide’s exact molecular weight from the CoA for molar calculations.
3. Initial Wetting: Add a small volume (10–20% of final) of chosen diluent along the vial wall. Gently swirl or tap—do not vortex.
4. Bring to Final Volume: Add remaining diluent in small increments, gently mixing until fully clear. Maintain cold handling.
5. Optional Clarification: If permitted by your protocol, pass through a 0.22 µm low protein-binding sterile filter to remove particulates.
6. Aliquot Immediately: Dispense into single-use, labeled microtubes to eliminate repeat freeze–thaw cycles.
7. Store per SOP: Short term at 2–8 °C (days), longer term at −20 °C or −80 °C; protect from light. See Storage Best Practices.
8. Document: Record lot, concentration, diluent composition, pH, prep date/time, and storage conditions. Attach CoA.

Worked Example (Concentration Math)

Objective: Prepare 1 mL of retatrutide at 1 mg/mL from a 2 mg lyophilized vial.

• Mass available = 2 mg → To get 1 mL at 1 mg/mL, dissolve 1 mg in 1 mL diluent; aliquot the remaining 1 mg separately for future use.
• Molar prep (if MW = X g/mol): Desired 100 µM in 1 mL requires 100 nmol → mass = (100 nmol × X g/mol) = (0.0000001 × X) g.

Note: Use the exact molecular weight from your CoA; avoid rounding in regulated workflows.

Troubleshooting

• Persistent Haze: Chill and allow to equilibrate; consider minimal DMSO pre-wet or 0.1% acetic acid. Avoid vigorous mixing.
• Foaming: Indicates over-agitation. Rest on ice until bubbles dissipate; gently invert only.
• Precipitation After Dilution: Stepwise dilution, maintain slightly acidic pH, and keep cold. Validate ionic strength compatibility with your assay.
• Loss on Filtration: Use low protein-binding membranes; pre-rinse with buffer; quantify recovery if yield is critical.

Quality & Documentation Controls

• Verify purity and identity via CoA (HPLC/MS). For sensitive studies, spot-check by HPLC post-mix. See Peptide Purity for standards.
• Label aliquots with concentration, diluent, date, and storage temp; implement barcode or LIMS tracking.
• Log any temperature excursions and corrective actions per SOP.

FAQs

Which diluent is best?

Begin with sterile WFI or 0.9% NaCl. If solubility is limited, titrate in mild acid (e.g., 0.1% acetic acid). For hydrophobic sequences, pre-wet with minimal DMSO, then dilute.

Can I vortex?

Avoid vortexing; it can denature or aggregate sensitive peptides. Gentle swirling or inversion is preferred.

How long is a reconstituted aliquot stable?

Sequence- and buffer-dependent. As a rule of thumb, keep aliquots cold, minimize light/oxygen, and use within your validated window. Confirm by HPLC or functional assay when stability is critical. See Storage Best Practices for detailed handling parameters.

Compliance Reminder

All peptide products are for laboratory research only. Follow institutional SOPs, biosafety policies, and local regulations. Not for diagnostic or therapeutic use.