Lab Documentation and Reproducibility: A Practical Guide

Research reproducibility depends less on heroic effort than on ordinary record-keeping. When another lab, or the same lab a year later, cannot repeat a result, the cause is often not fraud or incompetence but missing information: which lot of a reagent was used, how long a solution sat at room temperature, what the vehicle actually contained, or which samples were excluded and why. Good documentation captures those details at the moment they happen, when they are still easy to record.

This guide sets out what peptide researchers should document, with particular attention to the material itself. Lot numbers, certificates of analysis, storage conditions and preparation steps are easy to overlook and difficult to reconstruct afterward, yet they frequently explain why two apparently identical experiments disagree.

The reproducibility problem

Concern about reproducibility in preclinical research is long-standing and well documented. Scientists at pharmaceutical companies have reported being unable to reproduce a large share of published preclinical findings they attempted to build on, and a widely cited survey of researchers published in Nature found that most respondents had at some point failed to reproduce another group’s experiment, and many had failed to reproduce their own. The causes identified in this literature are varied: small sample sizes, selective reporting, inadequate statistical design, and incomplete methods sections that leave out details another lab would need.

Reagent variation is part of that picture. Antibodies, cell lines and synthetic peptides can all differ from batch to batch, and if the batch is not recorded the difference becomes invisible. For peptides, purity, counterion content, water content and the profile of related impurities may vary between synthesis runs. Understanding batch traceability and lot numbers is the starting point for making that variation visible rather than leaving it as an unexplained source of noise.

What to record

A useful test for any record is whether a competent colleague, with no access to you, could repeat the experiment from it. That standard is demanding, and it shapes what belongs in the notebook.

Materials

For each peptide or reagent, record the name and sequence, supplier, catalog or product identifier, lot number, date received, the form supplied (for example lyophilized acetate or trifluoroacetate salt), and the storage location. Note the reference to the corresponding certificate of analysis. For cells, record the source, authentication status, passage number and mycoplasma testing date.

Methods and preparation

Record how each solution was prepared: the mass weighed or volume taken, the solvent and its lot, the final concentration and how it was calculated, including whether net peptide content was taken into account. Note the date and time of preparation, aliquot volumes, and any deviation from the written protocol, however minor it seemed at the time.

Data and analysis

Link raw data files to the experiment that generated them, with instrument settings and software versions. Record how samples were allocated to groups, whether outcome assessment was blinded, and any exclusions with the reason and the point at which the decision was made. For animal studies, the ARRIVE 2.0 checklist is a practical guide to what a reader will need, and its essential items map neatly onto notebook headings.

Lot numbers and COAs

The lot number is the link between a vial on the bench and the analytical data describing it. A certificate of analysis typically reports identity, often by mass spectrometry, and purity, often by HPLC, for that specific production batch, and may include appearance, water or counterion content and storage recommendations. Our guide to how to read a peptide COA explains each section.

Good practice is to record the lot number at receipt, label every aliquot with it, and archive a copy of the certificate with the experimental records rather than relying on being able to find it later. Many suppliers provide a way to retrieve the certificate of analysis for a given lot, which makes it straightforward to file the matching document at the moment the material arrives. When a result changes after a new lot is introduced, comparing the two certificates is one of the first diagnostic steps. Where a project depends on a single lot, some labs reserve enough material to complete the work, or run a bridging experiment comparing old and new lots side by side before switching.

Storage and handling logs

Peptides can degrade through oxidation, deamidation, hydrolysis and aggregation, and the rate depends on temperature, moisture, light, pH and the number of freeze-thaw cycles. A material that met its specification on the certificate may not match it after months of poor storage, so the conditions between receipt and use belong in the record.

A simple storage log notes the freezer or refrigerator, its monitored temperature, the date each vial was opened, when solutions were prepared and aliquoted, and how many times each aliquot was thawed. Temperature excursions, such as a freezer alarm or a shipment that arrived warm, should be logged with their duration and the decision taken about the affected material. These entries take seconds to write and can save weeks of troubleshooting.

Templates

Structured templates reduce the chance that a field is forgotten. They can live in a paper notebook, an electronic lab notebook or a shared spreadsheet, as long as entries are dated, attributable and not overwritten. The FAIR principles, which call for data to be findable, accessible, interoperable and reusable, offer a helpful framework for deciding how records should be named and stored.

Record	Minimum fields
Material receipt	Name and sequence, supplier, product identifier, lot number, date received, form and counterion, storage location, COA reference
Solution preparation	Date and time, operator, mass or volume, solvent and lot, final concentration and calculation, aliquot volumes, labels
Storage log	Location, temperature record, open date, thaw count per aliquot, excursions and actions
Experiment	Protocol version, deviations, group allocation, blinding, controls used, raw data file links, exclusions with reasons

The COA reference field is worth making mandatory. Linking it to the supplier’s COA lookup page or attaching the PDF directly means that anyone reviewing the experiment can confirm what material was used without searching through email. The same principle applies to the controls described in our article on experimental controls in peptide research, since scrambled peptides and positive controls need their own lot records.

Making documentation routine

Reproducibility is built from small, consistent habits: recording the lot number on arrival, logging each thaw, noting the deviation when it happens rather than at the end of the week. None of these steps is difficult, but together they make it possible to explain a discrepant result instead of simply abandoning it. They also make published methods more complete, which is ultimately how other laboratories are able to build on the work.

References

1. Begley CG, Ellis LM. Raise standards for preclinical cancer research. Nature. 2012.
2. Baker M. 1,500 scientists lift the lid on reproducibility. Nature. 2016.
3. Percie du Sert N, et al. The ARRIVE guidelines 2.0: updated guidelines for reporting animal research. PLoS Biology. 2020.
4. Wilkinson MD, et al. The FAIR Guiding Principles for scientific data management and stewardship. Scientific Data. 2016.
5. Kanare HM. Writing the Laboratory Notebook. American Chemical Society; 1985.