ISO/IEC 17025 by industry
ISO 17025 for testing laboratories: what chemical and microbiological labs must show for accreditation
Clause by clause: ISO/IEC 17025:2017 requirements: every clause explained →
What changes when the laboratory tests chemistry and microbiology: why customers and regulators ask for accredited results, how to write a scope by method and matrix, where assessors sample method files, reference materials, media control, QC charts and PT schemes, and how one system serves customers, regulators and ISO 9001.
Key points
- Chemical and microbiological results are bought on trust: the customer or regulator usually cannot repeat the test, so accreditation for the named methods is what makes a report acceptable.
- The scope is written test by test, per matrix and per method, so a laboratory can accredit its core chemistry and microbiology first and extend later.
- Assessors sample the method file, the reference materials behind each calibration curve, the control charts, the proficiency testing record and the chain from sample receipt to signed report.
- Microbiology adds its own evidence: control of culture media, reference cultures, incubators and the aseptic technique of each analyst.
Why chemical and microbiological laboratories are asked for ISO/IEC 17025
A food manufacturer releasing a batch, a pharmaceutical company checking a raw material, an exporter proving a shipment meets limits: each relies on a number it cannot check itself. When that number comes from a contract testing laboratory, the first question in the tender or supplier approval is usually whether the test is on an accredited scope.
Where a regulator, public buyer or importing authority asks for results from an accredited laboratory, it means accredited for that specific test, and the national accreditation body is normally the route. Which body to use and how international acceptance works is covered in Choosing an accreditation body: Global ACI recognition and what it means.
Scope of accreditation for a chemistry and microbiology laboratory
A testing laboratory's scope lists each test by discipline, product or matrix, measured property, method and, where it matters, range. A chemistry line might be a residue in a named matrix by a stated chromatographic method; a microbiology line the detection of a named organism in a product group.
Three scope mistakes recur in this sector. Laboratories apply for every test on the price list, when a first scope of high-volume, customer-critical methods is faster to evidence. Matrices are written too broadly, so a method verified in water appears to cover soil or food. Sampling is claimed when the laboratory only receives samples others have taken. How to write the lines is covered in ISO/IEC 17025 scope of accreditation: fixed, flexible and how to write it.
Where the requirements bite in chemical and microbiological testing
| Requirement area | What it means in a testing laboratory | Evidence the assessor samples |
|---|---|---|
| Selection, verification and validation of methods | Standard methods verified in your matrices; in-house and modified methods validated for detection and quantitation capability, precision and recovery or trueness | Verification and validation files per method, the raw data behind them, the stated limit of detection and limit of quantitation with how they were derived, analyst authorisations |
| Metrological traceability and reference materials | Calibration curves and spiking built on reference materials with known values and a documented chain, and balances, pipettes and thermometers calibrated | Reference material certificates, working-standard preparation and expiry records, calibration certificates and intermediate checks |
| Facilities, equipment and consumables for microbiology | Separation of clean and contaminated work, controlled incubation and sterilisation, and culture media and reference cultures that perform as intended | Temperature records for incubators, fridges and autoclaves, media batch records with sterility and growth-performance checks, reference culture maintenance records |
| Handling of test items and technical records | Sample receipt, identification, condition on arrival, storage and disposal controlled so every result traces back to one sample, and chain of custody kept where customers or legal use require it | Sample receipt logs, rejection or acceptance-with-deviation records, custody forms, and worksheets from which a result can be reconstructed |
| Ensuring the validity of results | Quality control in each run plus proficiency testing schemes, with trends acted on before results go out | Control charts for blanks, check standards, spikes or duplicates, positive and negative controls in microbiology, the proficiency testing plan, results and the actions taken on any unsatisfactory score |
The method file is covered in Method verification and validation under ISO/IEC 17025 and scheme selection in Proficiency testing and interlaboratory comparison under ISO/IEC 17025.
ISO/IEC 17025 alongside customer, regulatory and quality requirements
Testing laboratories answer to customer specifications, the regulations of the sectors whose products they test and often a parent company's ISO 9001 system, and one management system can carry all of them. Option B allows a laboratory inside an ISO 9001 certified organisation to use that system for the management clauses, while the technical requirements for methods, traceability and validity of results still apply in full; see ISO 9001 vs ISO/IEC 17025: what accreditation adds.
Two neighbouring standards matter when you choose suppliers. Reference material producers work to ISO 17034 and proficiency testing providers to ISO/IEC 17043, and both can be accredited, which gives you a documented basis for approving them as external providers. A medical or clinical microbiology laboratory testing human samples usually follows ISO 15189 instead.
What an engagement with a testing laboratory looks like
Duration depends on the number of methods and matrices in the first scope, how many are in-house or modified and need validation, the state of calibration and reference material records, the dates of the next proficiency testing rounds, and how much quality control data has already accumulated. The laboratory and quality managers, the chemistry and microbiology section heads, the analysts to be witnessed and sample reception take part. With Design™, Sterling guides your team to build and own the system; with Drive™, Sterling takes on more of the documentation, method files, internal audit and readiness work so testing keeps moving.
How Sterling works with testing laboratories
Method files, control charts and records an assessor can follow from sample to report.
Our expert and experienced consultants work method by method with your analysts, from verification and validation through reference materials, media control and proficiency testing, then audit the technical clauses before the accreditation body arrives. Effivity holds the management system records and is included with the engagement, at no additional cost. Sterling does not accredit; the accreditation body assesses and decides. We ensure successful accreditation for our clients.
Book a free discovery callISO 17025 for testing laboratories: questions laboratory managers ask
Do we need to validate a standard test method under ISO 17025?
No, a published standard method used as written is verified rather than validated. You show that your laboratory achieves the method's performance with your staff, equipment and matrices; full validation is kept for in-house methods and, as our working rule, for published methods you have changed or use outside their stated scope.
Can chemistry and microbiology be accredited together under ISO 17025?
Yes, one laboratory can hold one accreditation covering both disciplines. The scope lists the tests of each discipline separately, and the accreditation body typically sends technical assessors with the right expertise for each.
How long does ISO 17025 accreditation take for a testing laboratory?
Plan on six to twelve months for a first accreditation. Method work, proficiency testing rounds on the provider's calendar, quality control data accumulating and the accreditation body's own steps set the pace.
Should a clinical microbiology laboratory use ISO 17025 or ISO 15189?
A laboratory testing human samples for patient care usually seeks accreditation to ISO 15189, the standard for medical laboratories. ISO/IEC 17025 fits microbiology testing of food, water, pharmaceuticals, the environment and other products.
ISO/IEC 17025 by industry
Every guide in the ISO/IEC 17025 series is written for one question and links back to the hub for the whole picture.
- ISO/IEC 17025 for calibration laboratories
- ISO 17025 case study
- ISO 17025 checklist
- ISO/IEC 17025 for chemical and microbiological testing
- Choosing an ISO 17025 accreditation body
- ISO 17025 common mistakes
- ISO/IEC 17025 for construction materials testing
- ISO/IEC 17025 for environmental laboratories
- ISO/IEC 17025 for food and agriculture laboratories
- ISO/IEC 17025 for government and forensic laboratories
- ISO/IEC 17025 for in-house manufacturing laboratories
Keep exploring
Explore more about ISO/IEC 17025
Watch a video on how to implement ISO 17025 here.
Watch a video on ISO 17025 requirements here.
ISO/IEC 17025 resources
Services for ISO/IEC 17025
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