The auditor asked for the certificate of analysis on a lot of 9 mm screw-thread vials, and what came back was a one-page PDF with a pass/fail table and no instrument ID, no calibration reference, and no statement of which standard the “pass” was measured against. The lot was fine. The paperwork was not. That single gap is where ISO 17025 traceability for chromatography products usually dies, and it is almost never the link most labs expect.
ISO/IEC 17025:2017 clause 6.5 requires metrological traceability for measurement results, and clause 6.4 requires that equipment and consumables affecting results be controlled. For a chromatography consumable, that means a chain from the number printed on your certificate back to a national or international reference, with a calibration status and an uncertainty at every hop. I have watched labs pass a full method audit and then fail a supplier qualification on exactly this point. The product was compliant. The traceability chain was not.
The four links in a consumable traceability chain, and the one that is almost always missing
An unbroken chain for a chromatography consumable has four links. Most labs can produce three on demand and stumble on the fourth.
- Link 1: the reference standard. A physical or documentary reference the measurement is compared to. For a vial, that might be a certified dimensional standard traceable to a national metrology institute (NIST in the US, NPL in the UK, PTB in Germany). For a column, it is the test mixture and the reference chromatogram the lot was run against.
- Link 2: the measuring instrument. The caliper, the balance, the GC or HPLC used to generate the lot data, with a current calibration certificate that itself traces to a national standard. A caliper calibrated against a gauge block whose certificate is expired is not traceable.
- Link 3: the measurement record. The raw data, the operator, the date, the environmental conditions if relevant, and the uncertainty of the measurement. A certificate that says “dimensional check: pass” has no measurement record.
- Link 4: the link from measurement to the specific lot you received. This is the one that breaks. The manufacturer can trace the instrument. It can trace the reference. It often cannot trace the individual lot number on the box in your hand back to a specific measurement event, because the certificate is a template with a lot number stamped on it and the underlying data is batch-level, not lot-level.
Link 4 is the failure point because it is expensive to maintain and invisible to most customers. A supplier that runs a lot-level dimensional check on 30 vials out of 10,000 and keeps the raw data has a defensible chain. A supplier that runs a design-verification study once per product line and reuses the certificate has a chain that ends at the product, not the lot. Your auditor, if they are thorough, will ask for the lot.
What a defensible certificate of analysis for a chromatography consumable actually contains
I have read several hundred CoAs. The ones that survive a supplier audit share a specific set of fields. The ones that do not are usually missing three or four of them, and the missing ones cluster around the same place.
| Field | Why it matters | Typical failure |
|---|---|---|
| Lot number and manufacture date | Links the certificate to the physical product | Lot number on CoA does not match the box |
| Test method and standard reference (e.g., ASTM E691, ISO 4799, GPI 502) | Defines what “pass” means | “Per internal spec” with no reference |
| Instrument ID and calibration due date | Link 2 of the chain | Instrument named, no calibration reference |
| Measured value, tolerance, and uncertainty | Link 3 of the chain | Pass/fail with no number |
| Sample size and sampling plan | Defines the statistical claim | “n = 10” with no AQL stated |
| Reference standard ID (e.g., NIST SRM number) | Link 1 of the chain | No reference standard named |
| Authorized signatory and date | Accountability | No name, no date |
The most under-appreciated field is the sample size and sampling plan. A certificate that says “dimensional check passed” on a lot of 50,000 septa tells you nothing unless you know how many were measured and against what acceptance quality limit. ISO 2859-1 is the reference most suppliers should be citing and most do not. If the CoA says n = 10 out of 50,000 with an AQL of 1.0, you can compute the confidence. If it says nothing, you cannot.
Where the chain breaks in practice: three field cases
Case 1: the septa that passed dimensional check and failed puncture count
A lab running a headspace GC method with a 23-gauge needle started seeing coring at around 60 injections on a lot of PTFE-faced silicone septa. The CoA showed a dimensional check and a durometer reading, both passing. The measurement that identified the problem was a puncture-count test on 20 septa from the suspect lot against 20 from the previous lot, using a torque-controlled autosampler and counting visible cores under 10x magnification. The suspect lot averaged 62 punctures before first core, the previous lot 118. The CoA had no puncture-count field at all. The fix was a supplier change to one that publishes a puncture-count specification with a stated needle gauge, a stated injection volume, and a stated test method. That is what a traceable claim looks like for a septum. The dimensional certificate was real. It just did not measure the property that mattered.
Case 2: the vial that was 0.3 mm short and the certificate that could not prove it
A lab on a 9 mm screw-thread autosampler started getting intermittent “vial not detected” errors on one lot. The measurement was a go/no-go check with a calibrated height gauge on 50 vials from the lot. The lot mean was 31.7 mm against a nominal 32.0 mm with a tolerance of ±0.2 mm, so the mean was out of tolerance and the tail was worse. The supplier’s CoA claimed conformance to the drawing. When the lab asked for the raw measurement data, the supplier could produce a design-verification report from 2019, not a lot-level measurement. The chain ended at Link 3. The fix was not a new supplier immediately; it was a clause in the purchase order requiring lot-level dimensional data on request, plus an incoming inspection of 10 vials per lot with a calibrated gauge. That is a workaround, not a solution. The real solution is buying from a supplier whose CoA includes the measured values and the instrument ID. Sources like Vials With Caps publish the dimensional and closure-torque data at lot level, which is what the auditor will ask for.
Case 3: the column that drifted and the reference chromatogram that was missing
A lab running USP <621> suitability on a C18 column saw the tailing factor on a basic analyte climb from 1.4 to 1.9 over three lots. The CoA showed a retention-time and efficiency check. It did not show the reference chromatogram or the test mixture composition. Without those, the lab could not tell whether the column had changed or the method had. The measurement that resolved it was a side-by-side injection of the current lot against a retained sample from the original qualifying lot, on the same instrument, same day. The current lot’s tailing factor was 1.85; the retained sample was 1.42. The column had changed. The supplier had switched the endcapping reagent. The CoA was accurate and useless, because it measured the wrong property against an unspecified reference. The fix was a supplier questionnaire that asks for the test mixture composition and the reference chromatogram, and a policy of retaining a qualifying sample from every new column lot.
The measurement that links the supplier’s instrument to your result
Traceability is not a document. It is a chain of measurements, and the chain has to close on the number that affects your chromatography. For a vial, that number is the dimensional tolerance that determines whether the needle hits the septum center. For a septum, it is the puncture count and the reseal force. For a column, it is the retention and selectivity against a defined test mixture. For a filter, it is the extractable profile against a defined solvent.
The question to ask a supplier is not “are you ISO 17025 accredited.” Most are not, and they do not need to be. The question is: which of your measurements are made under a calibration program traceable to a national standard, and can you show me the certificate for the instrument that measured my lot? That is the question that separates a supplier with a real chain from one with a template.
If you need a starting point for what a properly documented chromatography consumable looks like, the catalogs at Agilent and Thermo Fisher publish lot-level performance data for columns and many consumables, and Restek publishes reference chromatograms and test-method documentation that most suppliers do not. Use those as the benchmark for what you should be asking a smaller supplier to provide.
The acceptance criteria I use for a supplier’s traceability package
When I qualify a supplier for a chromatography consumable that affects a regulated result, I score the traceability package against six criteria. A supplier that fails more than two is not disqualified, but the product goes on incoming inspection and the purchase order gets a data clause.
- Reference standard named and current. The certificate names the standard (NIST SRM number, ISO reference, or an internal standard with a stated calibration history). If it says “internal standard” with no history, score zero.
- Instrument ID and calibration due date on the certificate. Not on request. On the certificate.
- Measured value plus tolerance plus uncertainty. A pass/fail is not a measurement. Demand the number.
- Sampling plan stated. Sample size, lot size, AQL, and the standard used (ISO 2859-1 is the usual one).
- Lot-level data available on request within 5 business days. If they cannot produce it, the chain ends at Link 3.
- Change notification clause. Any change to resin, endcapping, septa formulation, or molding tool requires written notice before shipment. Case 3 above would have been caught by this clause.
For a regulated method, I also want the supplier to state which SW-846 or USP chapter the product is qualified against, if any. That is not the same as traceability, but it tells you whether the supplier understands the difference between a product specification and a method requirement.
What to do when the supplier cannot close the chain
Most suppliers of commodity vials and septa cannot close Link 4 on demand. That is a fact of the market, not a moral failing. The practical response is a three-tier incoming inspection program keyed to the criticality of the consumable.
| Tier | Consumable type | Incoming check | Frequency |
|---|---|---|---|
| Tier 1 (critical) | Autosampler vials, septa, caps, syringe filters for trace analysis | Dimensional check (10 units, calibrated gauge), puncture count (20 units, defined needle), extractable blank | Every lot |
| Tier 2 (method-affecting) | Analytical columns, guard cartridges, SPE sorbents | Reference chromatogram against retained qualifying sample, system suitability per method | Every lot |
| Tier 3 (general) | Glassware, tubing, general lab plastic | Visual and certificate review | Annual or on supplier change |
The dimensional check for a 9 mm vial is a height gauge reading against the drawing tolerance, typically 32.0 ± 0.2 mm for height and 6.0 ± 0.1 mm for the neck OD on a standard 2 mL vial. The puncture count for a silicone septum with a 23-gauge needle should clear 100 punctures before first core under a defined autosampler method. The closure torque for a screw cap is typically 0.6 to 1.2 N·m depending on cap design; over-torque distorts the septum and creates the coring you were trying to prevent. These are the numbers I put in an incoming inspection SOP, and they are the numbers I ask a supplier to publish.
The decision rule
Buy chromatography consumables from a supplier that can name the reference standard, the instrument, and the lot-level measurement behind every certificate, and treat a supplier that cannot as a Tier 1 incoming-inspection item rather than a qualified source. If you cannot get lot-level data, you own the traceability chain yourself, and that means a calibrated gauge, a defined puncture-count method, a retained qualifying sample, and a written SOP. The certificate is the supplier’s claim. The measurement is yours. ISO 17025 traceability for chromatography products is only as strong as the link you can prove, and in most labs that is the lot-level measurement, not the accreditation logo. If you are building that program, start with the consumables that touch the sample path: the vials, septa, and caps from Vial Supplier, the columns and filters from Aijiren, and the full catalog at Chromatography Products. Put the data clause in the purchase order before the next audit, not after.
References & further reading
Related resources from our lab consumables network:
- Chromatography Products at chromatographyselling.com
- Aijiren at aijirentech.com
- Vials With Caps at vialswithcaps.com
- Vial Supplier at vialsupplier.com
External references and standards: