Laboratory testing glossary

These are the terms a test report uses to say precisely what was measured, in what, by which method, and how sure the laboratory is of the number. Reading them correctly is the difference between a result you can act on and a number you are guessing at.

If a term here decides whether your sample can be tested at all — the matrix, above all — settle it before anything ships. The submission guide covers what has to travel with a sample; the request form is where you name the matrix and the determination.

CFU

Colony-forming unit — the unit a microbiological count is reported in. It counts the colonies that grow on a plate rather than individual cells, because a colony may start from one cell or from a clump.

Detection vs enumeration

Detection answers whether an organism is present in the portion of sample examined; enumeration answers how much of it is there. They are different methods, and a presence result cannot be turned into a count.

Limit of detection (LOD)

The smallest amount of the substance or organism a method can reliably distinguish from nothing. Below it, “not detected” means the method could not see it — not that it is absent.

Matrix

The material the sample is made of — milk, meat, water, a surface swab. Methods are validated per matrix, which is why a laboratory asks what the sample is before it confirms the test.

Method reference

The published method a determination was run to, named on the report. It is what lets another laboratory repeat the work, and what a specification or a regulator judges the result against.

Measurement uncertainty

The quantified doubt around a reported value — the interval within which the true value is expected to lie. Every measurement carries it; a competent laboratory can state it.

A calibration certificate is a record of what an instrument read against a reference, not a pass stamp. These terms carry the substance of it — what the instrument did before adjustment, what the laboratory is allowed to claim, and how the whole exercise connects to anything outside the room.

The calibration pages on this site describe the disciplines themselves; the accreditation page publishes the capability behind them, line by line.

As-found / as-left

As-found is what the instrument read when it arrived, before any adjustment; as-left is what it read afterwards. The as-found data is what tells you whether the measurements made since the last calibration can be trusted.

CMC

Calibration and measurement capability — the smallest uncertainty a laboratory may claim for a given measurement under its accreditation. It is published per line on the scope annex, and no certificate may claim better than it.

Traceability

An unbroken chain of calibrations connecting a measurement back to national or international references, each step with a stated uncertainty. It is what makes a result comparable to one made anywhere else.

Reference standard

The instrument or artefact a laboratory calibrates against, itself calibrated further up the chain. Its quality caps the quality of every calibration made with it.

Calibration interval

How long an instrument runs between calibrations. It is set from the instrument’s stability, how hard it is used and what rides on its readings — a risk decision made by the owner, not a figure fixed by any standard.

Hysteresis

When an instrument reads differently at the same point depending on whether the value was rising or falling towards it. Common in pressure gauges, and one reason a calibration approaches each point from both directions.

Accreditation vocabulary exists to draw a boundary: which body vouches for which laboratory, for which work, checked how. The single most useful habit is asking for the scope annex rather than the certificate — the certificate says a laboratory is accredited, only the annex says for what.

Our own certificates and full scope annex are published on the accreditation page, including the fields that are not on it. The guide on reading a laboratory accreditation walks through how to check any laboratory, not just this one.

Scope annex

The document listing exactly what a laboratory is accredited for — parameters, matrices, ranges and capabilities. It is a separate document from the certificate, and it is the one worth reading.

ISO/IEC 17025

The international standard for the competence of testing and calibration laboratories. Accreditation to it is what stands behind a test report or a calibration certificate.

ISO/IEC 17020

The international standard for bodies performing inspection — examining a product, process or installation and reporting conformity. A different activity from testing, under a different standard.

Accreditation body

The authority that assesses laboratories against the standard and grants accreditation. In Saudi Arabia it is the Saudi Accreditation Center, and it maintains the public register a certificate can be checked against.

Proficiency testing

A scheme in which laboratories analyse the same blind sample and the results are compared. It is how a laboratory — and its accreditation body — checks that competence holds at the bench, not just on paper.

Regulatory documents use laboratory results as evidence, and these are the terms that frame what the evidence has to show. Each of them is treated at working depth in the guides — what a stability study has to demonstrate behind a date is covered in the shelf-life guide, and where a Certificate of Conformity sits in clearance is covered in the import guides.

A definition tells you what the word means. The guide tells you what the regulator expects the document to contain — read the definition here, then the guide before you commission anything.

MRL

Maximum residue limit — the highest level of a pesticide or veterinary drug residue legally permitted in a food. A residue result is judged against the MRL for that substance in that commodity.

Certificate of Conformity (CoC)

A document declaring that a product or consignment meets the requirements applying to it, commonly supported by test results. It is the paper that most often carries laboratory work into a clearance file.

GSO

The GCC Standardization Organization, whose Gulf standards Saudi Arabia applies to food and consumer products. When a specification names “a GSO standard”, that standard is the requirement the result is judged against.

Technical regulation

A standard an authority has made mandatory — compliance is a legal requirement, not a choice. Labelling and safety requirements for food typically arrive this way.

Stability study

A study that holds a product under its intended storage conditions and tests it at defined checkpoints to establish its shelf life. The date printed on a pack is expected to be supported by one.