Laboratory handling best practices

Traceability starts at receipt

Record the lot number, receipt date and observed condition of every vial as it arrives, and check the shipment temperature indicator if one is included. A result recorded against a lot number can be reconciled with the certificate of analysis for that lot; a result recorded against a compound name cannot.

Keep the certificate of analysis with the lot record rather than filing it separately. When an anomaly appears months later, the ability to look up measured content and purity for the exact vial used is what separates a resolvable question from an unrepeatable experiment.

Aseptic technique

Reconstituted peptide solutions are nutrient-rich and unpreserved unless bacteriostatic diluent was used. Work in a laminar flow hood where available, swab the stopper with 70% isopropanol and allow it to dry before piercing, and use a fresh sterile needle or filter tip for each access.

Where a solution must be sterile and heat cannot be used, filtration through a 0.22 µm low-protein-binding membrane is standard. Note that some membrane chemistries retain a measurable fraction of peptide, so filtration should be validated before it is used ahead of quantitative work.

Labware

Choose low-binding polypropylene for dilute solutions. Avoid transferring peptide stocks through long runs of narrow tubing where surface-area-to-volume ratio is high. Pre-rinsing a tip with the solution being pipetted reduces variable loss between replicates.

Documentation of deviation

Record thermal excursions, extra freeze-thaw cycles, and any observation of haze or particulate. These notes cost seconds and are the first thing you will want when a dataset behaves unexpectedly. A lot with a documented excursion can be re-assayed; a lot with an undocumented one is simply unknown.