Chain of custody, end to end.

What chain of custody means here

Chain of custody (CoC) is the continuous, contemporaneously-documented record of every person who handled a sample, every place it was stored, and every temperature it experienced between two points. For us, those two points are (a) the moment an intake technician opens a blind-purchased package and (b) the moment the contract lab loads an aliquot onto an instrument. Any gap in that record — a missing signature, an unexplained time window, a freezer logger blackout — means we cannot defend the resulting data as representative of the vial that arrived.

The structure we use follows the general CoC discipline required by forensic and clinical analytical labs: each custody event is a timestamped row, signed by the person relinquishing and the person receiving, with no retroactive edits permitted.¹

Barcodes and the per-sample record

At intake, each vial (or each receiving unit, when a vendor ships multiple vials of the same product as a single lot) is assigned a Code-128 barcode printed on a cryo-rated label. The barcode encodes an internal sample ID of the form OA-YYYY-NNNNN that is not publicly derivable from the vendor, peptide, or purchase details. That ID is the join key for every downstream record:

• Purchase record (order number, vendor, date, alias used)
• Intake photos (outer packaging, inner packaging, vial, label)
• Freezer log (every open/close event, temperature excursions)
• Transfer form to the analytical lab
• Lab intake form (signature, condition on receipt, storage location at the lab)
• Raw instrument files (HPLC chromatogram, MS spectrum, LAL plate data)
• Final COA and any remediation notes

Scanning the barcode in our internal system pulls up the full record. Nothing on that record can be edited after signature; corrections are made by appending a new signed entry that references the prior one. This is the same discipline used by clinical laboratories under CLIA for specimen handling records.

Freezer-log discipline

Lyophilized peptides are typically stored at −20 °C for medium-term retention and −80 °C for long-term retention or reconstituted aliquots. Published stability data for a range of therapeutic peptides confirms that repeated temperature cycling and prolonged ambient excursions are the dominant degradation pathways short of light exposure.²

Our freezer is on a continuous-recording temperature logger that samples every sixty seconds, with data retained indefinitely. An excursion alarm fires if the internal temperature rises above −15 °C for more than ten minutes, and a daily summary is written to the freezer log automatically. Manual entries — "sample OA-2026-01042 removed for transfer at 14:03, logger reading −19.4 °C" — are added by technicians on each open-close event. If a freezer is opened without a corresponding log entry, the gap is flagged and any samples removed during that window are treated as chain-broken until reconciled.

The handoff to the contract lab

When a batch of samples is ready for testing, they are packed together for transfer. The transfer packet includes:

1. An insulated shipper with documented-performance phase-change packs or dry ice, chosen to hold the target temperature for at least twice the expected transit time.
2. A single-use temperature data logger placed in the shipper alongside the samples. The logger is read and its trace is archived after the lab receives the package.
3. A chain-of-custody form listing every barcode in the shipment, the sending technician's signature and timestamp, and pre-printed receiving fields for the lab.
4. A tamper-evident seal across the shipper closure. The seal ID is recorded on the CoC form.

At the lab, the intake technician verifies the seal is intact, photographs the unopened shipper, opens it, reads the temperature logger, and signs each vial in against its barcode. Anything that fails this verification — broken seal, excursion on the logger, missing vial, label illegible — is recorded on the CoC form as an exception before any sample is processed. We require the lab to send us the exception record within one business day; testing does not proceed until we have reviewed it.

What happens when the chain is broken

Chain breaks are handled by category, and none of them are handled by hiding the break:

• Minor, documented, non-material. A logger battery fails for the last thirty minutes of a ten-hour transit in which the shipper was still sealed and a redundant indicator strip shows no excursion. The test proceeds; the COA carries a note.
• Material exception with intact sample. A tamper seal arrives broken but the vial is visibly intact and the lab's receiving technician signs that observation. The sample is flagged chain-compromised on the public assay page. If it is tested, its result feeds only a sensitivity check — it does not determine a pass or fail on the supplier.
• Material exception with damaged sample. A vial arrives cracked, leaking, or with a visible excursion on the shipper logger. The sample is not tested. A re-order is placed, blind, from the same vendor listing, at our expense.
• Our fault. An internal freezer excursion, a lost barcode, or a transfer-form error that cannot be reconstructed. The affected samples are retired. We eat the cost of the re-order and we log the incident on our public corrections page even if no result was ever published.

Retention

CoC forms, freezer logs, shipper logger traces, and lab exception records are retained indefinitely and are available to researchers on request by assay ID. We treat these as part of the public evidentiary record for any result we publish — a test we cannot document is a test we should not have reported.

¹ ASTM E1492, Standard Practice for Receiving, Documenting, Storing, and Retrieving Evidence in a Forensic Science Laboratory.
² Frokjaer & Otzen, "Protein drug stability: a formulation challenge," European Journal of Pharmaceutics and Biopharmaceutics, 2015. DOI 10.1016/j.ejpb.2015.03.032.