Reproducible research requires more than knowing a sample's name. Its history also matters: In what form was it supplied? What storage conditions were specified? Were there any deviations? This article explains how to record this information clearly.
Product-specific instructions take priority
A general temperature or shelf life is not a reliable storage instruction for every peptide. The sequence, formulation and condition of the sample matter. Manufacturer instructions must therefore match the specific material. Storage advice for a freeze-dried peptide cannot simply be applied to a solution.
Which factors are relevant?
Sigma-Aldrich identifies moisture, light, oxygen and repeated freeze–thaw cycles as relevant factors. Certain amino acids increase susceptibility to oxidation or changes in solution. The supplier recommends allowing refrigerated containers to reach ambient temperature while still closed before opening, to reduce moisture absorption. Such general guidance does not replace product-specific instructions.
A Waters application study specifically examines changes in a synthetic peptide after stress exposure. It demonstrates the value of chromatographic and mass spectrometric comparisons in assessing such changes. However, it does not establish a general shelf life for other peptides.
A simple template for the laboratory notebook
As an editorial aid to documentation, we recommend the following fields:
| Field | What to record |
|---|---|
| Identification | Product, batch, internal sample identifier |
| Initial condition | Form supplied, date received, container condition |
| Instructions | Storage instructions, including source and document version |
| Storage | Storage location, recorded conditions, known deviations |
| Laboratory use | Date opened, withdrawals and relevant changes in condition |
| Queries | Supplier responses and decisions about further use |
Frequently asked question: Is a sample unusable after a storage deviation?
This cannot be reliably decided from a single temperature reading or its appearance. First document the nature and duration of the deviation and obtain an assessment specific to the material. Whether further analysis is needed depends on the laboratory's research question and the available data.
Clear documentation prevents samples with unknown storage conditions from being compared unnoticed with other batches. For help interpreting analytical results, see the HPLC basics and the explanation of COAs. This article concerns laboratory samples and contains no instructions for human or animal use.