Laboratory guides
Vial labels and batch traceability
What belongs on a vial label, how to keep it readable through laboratory use, and why the batch identifier connects material with its analytical documentation.
Laboratory procedure
- 01
Label on receipt, not at the first experiment
Receipt is the best opportunity to reconcile the material and its accompanying documentation before they are separated. Before storage, compare the batch on the vial with the certificate of analysis when one is supplied and with shipment documentation where the identifier is repeated. Preserve the supplier’s original label and add your own without obscuring the original batch. Postponing labeling assumes the accompanying documents will still be available later.
- 02
Choose the label and ink for the actual environment
A container moved in and out of cold storage encounters condensation, glove abrasion and possible solvent splashes. Ordinary paper or ink may detach or smear, often taking the irreplaceable batch field with it. Choose suitable laboratory labels and solvent-resistant marking, then test the combination against the expected conditions before relying on it. Writing only on a cap is insufficient: screw caps can be exchanged, and a crimped vial’s flip-off cover is removed to expose the septum.
- 03
Copy the batch character by character and cross-check it
Batch identifiers often combine letters and digits, making similar characters, missing hyphens and transposed positions easy mistakes. Copy from the original rather than memory. Then verify from the new label back to the original document, deliberately checking each character. A second person can read the copied identifier while another checks the source. The aim is an independent comparison, not a second glance that repeats the same assumption.
- 04
Use unambiguous dates and record opening immediately
Received, opened and prepared are different events. Identify the event beside each date and use a full year-month-day format so the value does not change meaning across date conventions. A sealed vial and an opened vial do not have the same handling history; the applicable storage conditions depend on the compound documentation.
- 05
Give every aliquot its parent batch link
Each container prepared from the original inherits the parent batch and gains its own internal identifier, solvent, nominal concentration, preparation date and preparer’s initials. Without that inherited link, the child container becomes an orphan: material is present, but its analytical record can no longer be reliably recovered. Preserve the link during subdivision rather than reconstructing it later.
- 06
Complete the record and close out empty containers
Write the label and laboratory record in the same session. Repeat batch, dates and responsible person in the record and use a controlled identifier to link the physical container to it. When a vial is exhausted or discarded, update its status and remove or invalidate the label according to the laboratory procedure so an empty container cannot return to the bench appearing to be available material.
The label is the document that stays with the material
A vial commonly has three associated records: shipment documentation, a laboratory record and a label. The first two live in an archive or notebook; the third remains attached to the container. Months later, someone opening a storage drawer may initially see only that label. Write it for the person who encounters the material without the original context or an available colleague to ask.
This determines how information should be divided. Label space is limited and text must remain legible, so include enough to identify the material and an identifier that retrieves the remaining record. Detailed calculations, provenance, incidents and responsibilities belong in the controlled record rather than being squeezed onto the glass.
- Compound name as given in the source documentation, without improvised local abbreviations.
- Batch identifier copied and checked character by character.
- Date with the event explicitly identified: received, opened or prepared.
- Initials or another controlled identifier for the person labeling or preparing the material.
- For laboratory-prepared containers, the solvent and calculated nominal concentration, with units.
- The research-use-only designation, so the container’s intended scope remains clear if it is moved.
The batch points to a record rather than describing chemistry
Most label fields describe the contents. A batch identifier serves a different purpose: it is a reference to a particular production or controlled material record. A certificate of analysis normally reports results for the identified batch or sample, not every material bearing the compound name. Sequence and molecular mass describe the intended molecule; evidence that a particular supplied material matches the specification must be linked to that batch and the reported tests.
A certificate with a different batch identifier cannot simply be treated as the vial’s certificate. Two vials with the same product name and catalog number can come from different batches with different analytical records. If the laboratory record captures the compound but omits the batch, later replication or investigation may be unable to establish which documented material generated the result.
How traceability breaks, and how to make the break visible
Traceability usually breaks during routine handling: transferring into a new container and recording only the name, reusing a container without removing its old label, writing on an interchangeable screw cap, using ink erased by condensation, or opening two batches of the same compound without clearly separating them on the bench.
Not every mistake can be prevented, but missing information can be made conspicuous. A mandatory batch field leaves a visible blank; a record system that requires the batch before accepting an entry stops the process at the right point. An unreadable container is not “probably” a known material. Inferring identity from its storage position or someone’s memory creates an unsupported record that can look more reliable than it is.
Questions and answers
What should I do with an unlabeled vial or an unreadable label?
Remove it from use. Do not infer identity from its position, appearance or someone’s memory. Record it as unidentified material and follow the laboratory’s controlled disposition procedure. If the problem recurs, review the labeling process and materials rather than treating each discovery as an isolated operator error.
Is the batch number the same as the catalog or CAS number?
No. A CAS number identifies a registered chemical substance or form; distinct salt forms may have separate registrations. A catalog number identifies a supplier’s product or presentation. A batch identifies a particular production or controlled material group. Two vials can share catalog and CAS identifiers yet belong to different batches with different certificates. The batch link is needed to recover the appropriate analytical record.
How should I label a solution prepared from a vial?
Include its internal identifier, the parent vial’s batch, solvent, calculated nominal concentration with units, preparation date and preparer’s identifier. Preserve the parent batch link so the solution can be traced back to the source documentation. Use the compound’s documented storage conditions and period rather than assuming them from another preparation.
Where is the batch identifier, and how do I match it to the certificate?
Look on the original vial label and any accompanying shipment records. A certificate of analysis normally lists its batch or sample identifier alongside the compound information, often in the heading. Compare the identifiers character by character. If they differ, request clarification and the correct batch document from the supplier rather than accepting the certificate merely because the compound name matches.