Tailored services

WEPAL/QUASIMEME offers a range of tailored services to laboratories worldwide.

Addition of determinands to an existing PT

Upon request determinands can be added to an existing PT scheme. WEPAL/QUASIMEME will assess whether  sufficient laboratories will provide data in order to be able to perform a meaningful  statistical evaluation and hence laboratory assessment.

WEPAL/QUASIMEME can organise a new PT if it considers the addition of a determinand to an existing scheme less appropriate, for instance in view of the size of the test sample .

Please send your request to info@wepal.nl or quasimeme@wur.nl.

New PT 's on request

For a specific group of determinands or a matrix not yet available, WEPAL/QUASIMEME can organise a new PT under the conditions that sufficient laboratories will participate in order to be able to carry out meaningful evaluations and that suitable materials (concentration, matrix and stability) can be prepared.

The matrix must have a relationship with the existing PT schemes (agricultural, marine, ecological, environmental). WEPAL/QUASIMEME will discuss options with the applicant.

Please send your request to info@wepal.nl or quasimeme@wur.nl.

PTs for specific purposes / target groups

On request WEPAL/QUASIMEME organizes proficiency tests for specific groups of determinands, for comparising a specific analytical procedure or a group of laboratories. Some examples:

a.    Local proficiency tests:

In some countries the procedures to analyse determinands (e.g. nutrients, extraction methods, characteristics of the material) are prescribed by law. It is possible to ask for a specific PT, or to include a specific determinand (group) in an existing programme.

b.    In-company proficiency tests:

For larger companies with more departments and laboratories (i.e. in different countries) WEPAL/QUASIMEME can organise in-company PTs for an independent comparation of the analytical results of the departments / laboratories.

c.     The organisation of validation of methodology for ISO

The International Organisation for Standardization (ISO) develops new international standards. In working groups new methods are developed by independent technical experts nominated by ISO members. From first proposal to final publication, developing a standard usually takes about three years. WEPAL/QUASIMEME organises for ISO international laboratory-evaluating programmes for environmental and agricultural laboratories. To obtain the data necessary for validation, WEPAL/QUASIMEME distributes samples with different characteristics out of the stock available. Participants are asked to perform the analysis according the described method and deliver the results to WEPAL. If the results meet the ISO criteria, they will be included in the ISO standard.

d.     Under the authority of International organisations

International organisations fund laboratories in developing/ low income countries to improve their performance on specific areas. Examples are specific materials (e.g. microplastics), specific determinands (e.g. C13 or N15) or analytical methods/ equipment (neutron activation analysis).

On request it is possible to compare the results of this specific group with the total number of participants.

Please send your request to info@wepal.nl or quasimeme@wur.nl

Development exercises / studies

For emerging pollutants / determinands or in case of poor comparability among laboratories analytical methodology may need to be refined. On request WEPAL/QUASIMEME offers development exercises to develop and improve the methodology, that may result in a new PT scheme on a regular base.

Part of these development exercises are workshops to focus on specific problems and to discuss achievements and corrective actions.

Please send your request to info@wepal.nl or quasimeme@wur.nl.


WEPAL/QUASIMEME organises workshops and conferences to support participating laboratories. The workshops provide an opportunity to focus on specific problems both in the laboratory and in the field and, with the aid of expert assistance, provide working solutions. Especially the QUASIMEME conferences provide a fora for the interchange of information and experience amongst marine scientists and to extend the QUASIMEME network. On request WEPAL/QUASIMEME organises workshops for these purposes in consultation.

Please send your request to info@wepal.nl or quasimeme@wur.nl.

Custom made reference materials

At your request WEPAL/QUASIMEME can prepare material, collected by your laboratory, into internal reference samples with consensus values.

Consensus values can be provided if the determinand/matrix is part of a WEPAL/QUASIMEME proficiency test and the concentration level of concentration is suitable to include the material in a round. WEPAL/QUASIMEME will provide information about the stability of determinands for the matrix based on its extensive experience.

Please send your request to info@wepal.nl or quasimeme@wur.nl.

Custom made reference materials: an example

The minimum amount of dry sample required is 50 kg for soil and sediment, 6 kg for plants, manure, compost or sludge and 15 kg of biological tissue.
WEPAL/QUASIMEME (re)dries, mills and subdivides your samples into representative subsamples using automated equipment (photograph).


 You will receive the following:

Soil Sediment Plant, manure, compost and sludge Biological tissue
Quantity 10 kg 10 kg 1 kg 3 kg
Portion size 100 g 150 kg 20 g 50 g
Package closed, sealed plastic flasks closed, sealed plastic flasks closed, sealed plastic bags or flasks Closed glass flasks

Homogeneity tests will be carried out on a selection of samples and on a limited number of elements. A part of the sample will be introduced into the corresponding WEPAL/QUASIMEME programme.


All samples are identified by your given sample name. With each sample you receive:

  • a WEPAL/QUASIMEME number;
  • results of the homogeneity test;
  • results of the proficiency test;
  • the analytical data.