Inventory so a sample is not stored twice under two names

A cohort of forty livers becomes eighty results, or zero, when one tube is filed under two names. The tube did not multiply. The inventory did. One sample needs one identity: a primary code that means that physical container and no other, plus a map that takes you to it without a fishing trip through a cold cabinet. The temperature you store it at still follows storing biological samples from fridge to freezer. The way you write the requirement down for someone else follows how to write a laboratory sourcing enquiry.

Labels, cryoboxes, and racks are in the laboratory plasticware catalogue. A freezer that can hold the map you designed is a laboratory procurement question and a quotation request. The identity rule is not something a cabinet can enforce for you.

The principle: one container, one primary identity

An identity is the string you promise will refer to one physical container. A sample in the biological sense, a piece of one liver, may be split into several containers. Each container then has its own identity, linked to the parent, because each container can be thawed, dropped, or left in a warm shipper on its own life. The parent is an alias relationship. It is not a licence to print the same code on three tubes and call them interchangeable without a record.

A second name is useful. Collaborators arrive with their codes. Notebooks use nicknames. The honest structure is one row, one location, and a list of aliases that do not create extra rows. The dishonest structure is two rows, two locations, and a hope that everyone remembers they are the same tube. They will not remember. One analyst will treat them as replicates. Another will conclude the sample was lost and aliquot the wrong neighbour.

How a tube grows a second name

The second name is born in ordinary politeness. A visiting student writes "P3 liver" on the lid because that is the phrase in the protocol. The database already has "LIV-014" for the same punch, entered by the person who collected it. Both strings are now on paper. Somebody types "P3 liver" as a new line so the student's sheet will match, and invents a location from memory, often the same box, sometimes a new box they mean to create later.

It is also born in rescue attempts. A label falls off. Rather than reconcile the map, someone assigns a fresh code and freezes the tube in a "to be identified" box that slowly becomes a second collection. Months later both codes are cited in a figure legend. The cohort is analysed twice, or the statistics silently include a duplicate.

Aliquoting causes a cleaner version of the same wound. The parent stays "LIV-014" and the aliquots are also "LIV-014" with no suffix. Use of aliquot B is recorded as use of the parent. The parent is then reported as still full, and someone thaws it as well. You have spent two freeze-thaw histories and called them one.

The map is part of the identity

A primary code without a place is a rumour. The map that belongs on the same row is specific: freezer, shelf or rack position, box, and coordinate inside the box. "Minus 80, somewhere on the left" is how doors stay open. The coordinate should be the one printed on the box grid you actually bought, so two people mean the same well.

When you move a box, the move is an edit to the row at the time of the move, not a note you will enter after the seminar. A box that lives in two places in the database will be searched for twice and will be re-created by a well-meaning person who does not find it the first time. That re-creation is the second name.

The label on the tube has to carry the primary identity in a form that survives frost and solvents, and it has to match the row. A label with only the nickname, while the database has only the formal code, is two names that have not yet been typed. Put the primary code on the tube. Put nicknames in the alias column. If the tube is too small, put the primary code on the tube and the nickname only in the system.

A cohort that almost got counted twice

Forty mouse liver samples are collected. The surgical sheet uses M1 to M40. The biobank sheet uses LIV-200 to LIV-239. Both are correct descriptions. Only one is the primary identity. The laboratory picks LIV-200 and the rest as primary, and types M1 into the alias column of LIV-200. The tube label shows LIV-200. The box map shows freezer A, shelf 2, rack 1, box 4, position B3.

A collaborator emails a plot that says M1 and M2 were outliers. You can translate, because the alias is on the row. You do not create "M1" as a new sample in freezer B. If someone already did, the repair is to merge: confirm there is only one tube, void the extra row, and keep the alias. If there are now two tubes because someone re-aliquoted under the belief that M1 was missing, you have two containers and you must say so. They are not replicates of a new animal. They are two containers from one draw, and the analysis plan has to know that or the cohort is inflated.

The same week, LIV-214 is on the map at shelf 2 and physically on shelf 4 after a power-cut move that was never written down. A new student does not find it, assumes it was used, and excludes the animal. The sample is not gone. The map is lying. Reconciliation is a physical check of one box against its rows, done often enough that a move cannot hide for a whole study. You do not need a heroic inventory of the entire building to catch this. You need the rule that a move without an edit is an incident.

What to record, and what to refuse

Failure modes

If two people can create identifiers without checking the alias column, you will grow duplicates. The control is a unique primary key and a habit of searching aliases before minting a code.

If the label adhesive fails at minus 80, the identity falls off even when the database is perfect. The label class is part of this explainer. A paper label that lets go when frost melts is an inventory failure, not only a stationery failure.

If a private notebook is the only place a nickname is translated, the translation leaves when the person leaves. The alias column has to live where the map lives.

If quarantine tubes are given a new identity "so the hold is obvious", you have renamed a sample in the middle of its life. Use a status on the same identity. A new code is for a new container.

Biosafety and research use

Identity does not change hazard. A tube of infectious material under two names is still the hazard the biosafety office assigned, and it may be stored in the wrong room if one of the names omitted the hazard flag. The WHO laboratory biosafety manual is the programme frame. Your institution assigns the flag. This inventory rule does not de-identify human-derived research material into anonymity you were not permitted to create, and it does not make a research tube a diagnostic record.

Culture collections ship strains with their own identifiers. Keep the collection identifier as an alias or as the primary code, consistently, and do not relabel a strain into a new organism by typing loosely. The ATCC culture guides show how a deposited strain arrives already named.

What to ask for when the map needs hardware

Ask for cryoboxes with a grid you can cite, labels rated for the cold you use, and racks that match the shelf spacing in the freezer you are specifying. Put the identity rule in the same quotation request only as a statement of format: primary code plus coordinate. Do not ask a supplier to clean up a historical duplicate cohort. That reconciliation is a laboratory task, done with the tubes in front of you and the spreadsheet constrained to one row per container.