Every importer eventually asks the same question in the same order. Can we test this ourselves, and if we send it out, does the laboratory have to be accredited. The answers are yes for some parameters, no for others, and the boundary is not about equipment. It is about what the result will be used for.
A result used to decide whether a line is drifting can be produced on your own bench. A result used to release a consignment against a legal limit, to answer a competent authority, or to support a claim against a supplier has to be defensible by someone who was not in the room. That is a different standard of evidence, and it is what accreditation is for.
The short version
| Dimension | In-house laboratory | Accredited third-party laboratory |
|---|---|---|
| Turnaround | Hours | Days to weeks depending on method |
| Cost per test | Low marginal cost | Per-sample fee, higher for trace methods |
| Method scope | Whatever you have equipped and validated | The accredited scope, method by method and matrix by matrix |
| Weight with an authority | Supporting evidence at best | Recognised, subject to scope |
| Weight in a dispute | Contested as self-interested | Normally accepted if named in the contract |
| Independence | None. You are testing your own product | Structural, and required by ISO/IEC 17025 |
| Best used for | Process control, screening, release of routine parameters | Legal limits, contractual limits, disputes, periodic verification |
What belongs in-house
In-house testing is the right home for anything you need quickly, frequently, and for your own decisions. In a frozen fruit or dried goods operation that typically means:
- Moisture content and water activity, measured by calibrated meter on every batch.
- Sieve analysis, calibre and defect classification against the agreed product specification.
- Sensory and organoleptic analysis against a retained reference.
- Net and gross weight verification, pack integrity and seal checks.
- Metal detection and, where installed, x-ray inspection verification.
- Temperature records and logger download at incoming goods inspection.
Two conditions make in-house data worth anything. Instruments must be under a documented calibration programme with traceable standards, and methods must be written down and followed by more than one person with comparable results. A moisture balance that nobody has calibrated in two years is producing numbers, not data.
Participation in a proficiency testing scheme is the cheapest way to find out whether your bench agrees with the rest of the world. It is a requirement for accredited laboratories and a sensible voluntary discipline for an in-house one.
What has to go outside
Send work to an accredited third-party laboratory when the result has to persuade someone who is not you. That covers four situations.
The first is regulatory limits. Maximum residue limits for pesticides, contaminant limits, and the criteria in the microbiological criteria regulation are legal thresholds. Results near a limit will be challenged, and the challenge will start with the method, the accreditation scope and the reported measurement uncertainty.
The second is contractual limits. If your contract specifies a maximum for a mycotoxin, a heavy metal or a microbiological parameter, and the consequence of exceeding it is rejection, the test that triggers rejection should be one the supplier agreed to in advance.
The third is anything requiring instrumentation you will not own: liquid chromatography tandem mass spectrometry for residue and mycotoxin work, inductively coupled plasma mass spectrometry for heavy metals, gas chromatography mass spectrometry for volatiles and some residues, and accredited pathogen work.
The fourth is verification of your own bench. Sending a proportion of routine samples out, on a defined frequency, is how you find out that your refractometer has drifted before a customer does.
What ISO/IEC 17025 accreditation actually means
ISO/IEC 17025:2017 sets general requirements for the competence, impartiality and consistent operation of testing and calibration laboratories. It covers management requirements and technical requirements together: personnel competence, equipment and metrological traceability, method validation, handling of test items, reporting, and the evaluation of measurement uncertainty.
The point buyers most often miss is that accreditation is granted against a scope. A laboratory is accredited for specified methods applied to specified matrices, not as a building. A laboratory accredited for multi-residue pesticide analysis in cereals is not automatically accredited for the same method in frozen berries, and a report for an out-of-scope test is not an accredited result even if the letterhead carries the accreditation mark. Ask for the current scope document, find the method and the matrix in it, and check the expiry date.
Cross-border recognition runs through the International Laboratory Accreditation Cooperation mutual recognition arrangement. Accreditation bodies are peer-evaluated against ISO/IEC 17011, and the arrangement covers testing and calibration laboratories under ISO/IEC 17025, medical laboratories under ISO/IEC 15189, and inspection bodies under ISO/IEC 17020. A report from a laboratory accredited by a signatory body is intended to be accepted in other signatory economies, which is why the accrediting body matters as much as the laboratory name.
Inspection is a separate discipline from testing. Pre-shipment inspection, tally and sampling supervision fall under ISO/IEC 17020, and a firm accredited as an inspection body is not thereby accredited as a laboratory.
Sampling decides the result
A laboratory reports on the sample it received. If the sample does not represent the lot, an accredited method on state-of-the-art instrumentation produces an accurate answer to the wrong question. Sampling is the largest source of variability in most food testing programmes and the part most often left undefined in a contract.
For attribute inspection, ISO 2859-1 provides sampling plans indexed by acceptable quality limit. Lot size and an inspection level give a code letter, the code letter and the acceptable quality limit give a sample size with accept and reject numbers, and switching rules move between normal, tightened and reduced inspection based on history. General inspection level II is the usual default; the special levels are for destructive or expensive tests.
For chemical parameters, Union legislation prescribes sampling methods for several contaminant and residue groups, and those methods, not a convenience grab sample, are what a competent authority will apply. For pesticide residues, Directive 2002/63/EC sets the Community method of sampling. Write the sampling method into the contract alongside the limit; a limit without a sampling method is not enforceable in practice.
Retained samples matter for the same reason. Keeping a sealed, representative retention from every lot, stored under the product’s own conditions, is what allows a dispute to be re-tested rather than argued.
Drafting the dispute clause
Write the umpire analysis clause before you have a dispute. A workable clause names five things:
- The parameter, the limit and the unit, with no ambiguity about wet or dry basis.
- The method, by standard reference and edition, and the matrix it is applied to.
- The sampling plan, by reference to ISO 2859-1 or the applicable prescribed method, and who draws the sample.
- The laboratory or the criteria for choosing one, requiring current accreditation covering that method and matrix.
- Who pays. The common formulation is that the party whose position the umpire result contradicts bears the cost.
Add how measurement uncertainty is treated. Two competent laboratories can return different numbers for the same sealed sample and both be correct within their stated uncertainty. Stating in advance whether the limit is applied to the reported result or to the result less expanded uncertainty removes the most common argument in a rejection.
The certificate of analysis should carry the method, the accreditation status, the uncertainty where relevant, the sample identity and the lot it belongs to. A certificate that lists only results and a pass statement is not evidence of anything.
A workable split
Most importers converge on the same architecture. Routine physical and organoleptic parameters are tested in-house on every batch. Regulatory and contractual chemical and microbiological parameters are tested by an accredited laboratory on a risk-based frequency, tightened for a new supplier and relaxed on a documented history. A proportion of in-house results is verified externally each year. Every lot has a retention. The dispute clause names the method, the sampling plan and the laboratory.
The routing detail for individual parameters, and which of them belong at origin rather than on arrival, is covered in the laboratory testing guide.
Vorezan’s position
Vorezan is an information platform. We are not a laboratory, an inspection body or an accreditation body, we do not issue or verify certificates of analysis, and we do not advise on the acceptability of a specific result. Accreditation scopes, prescribed sampling methods and legal limits change. Verify a laboratory’s current scope with its accreditation body, confirm limits and sampling methods in the applicable Union legislation, and take your own advice before rejecting or accepting a consignment.
