> For the complete documentation index, see [llms.txt](https://docs.rplpeptides.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rplpeptides.com/docs/faq/stability-faq.md).

# Stability FAQ

## 1. How is long-term stability determined?

Stability studies are conducted per ICH Q1A(R2) guidelines. Batches are stored at -20°C (long-term), 2–8°C (intermediate), and 25°C/60% RH (accelerated) conditions. Samples are tested at defined intervals for purity (HPLC), appearance, water content, and other quality attributes.

## 2. What degradation pathways are most common?

| Pathway      | Affected Residues         | Byproducts                                 | Prevention                             |
| ------------ | ------------------------- | ------------------------------------------ | -------------------------------------- |
| Oxidation    | Met, Cys, Trp             | Methionine sulfoxide, disulfide scrambling | Nitrogen atmosphere, light protection  |
| Deamidation  | Asn, Gln                  | Aspartic acid, iso-aspartate               | pH 4–6 optimal, low temperature        |
| Hydrolysis   | All peptide bonds         | Smaller fragments                          | Lyophilized state, < 1% water          |
| Dimerization | Cys, reactive side chains | Covalent dimers                            | Low concentration, reducing agents     |
| Aggregation  | Hydrophobic regions       | Soluble/insoluble aggregates               | Avoid vortexing, gentle reconstitution |

## 3. What is the recommended shelf life for lyophilized peptides?

Under recommended storage conditions (-20°C, desiccated, light-protected), lyophilized peptides maintain ≥95% purity for 24–36 months. Specific stability data is available per product in the Technical Data Sheet.

## 4. How long is reconstituted peptide stable?

| Storage Condition           | Typical Stability |
| --------------------------- | :---------------: |
| -20°C (single-use aliquots) |   Up to 6 months  |
| 2–8°C                       |      30 days      |
| Room temperature (25°C)     |    24–48 hours    |
| Repeated freeze-thaw        |     ≤ 3 cycles    |

## 5. How does pH affect peptide stability?

Optimal pH range is 4–6 for most peptides. Acidic pH (< 3) accelerates hydrolysis; basic pH (> 8) promotes deamidation and racemization. Always use buffered solutions (PBS, acetate, or citrate) for reconstitution when precise pH control is required.

## 6. Does RPL Peptide provide stability data for individual products?

Yes. Accelerated and real-time stability data is available for each product. Specific stability-indicating methods are used to monitor degradation products. Contact technical support for batch-specific stability data.

***

*For stability-related inquiries: <technical@rplpeptides.com>*


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