Why proficiency tests?

External quality assessment trials are crucial for ensuring a high analytical performance of testing laboratories. Samples, which contain test specimens, are sent to other laboratories and are analysed there. The results are assessed acording to criteria set by the organizer of the external quality assessment trials. This enables a comparison of the quality of various laboratories. The participating laboratories are enabled at the same time to recognize and to overcome analytical problems and deficits.

External quality assessment trials have been a permanent feature of quality assurance work in chemical/physical experiments for a number of years. But quality assurance for biological experiments is still in its infancy. However, successful participation in external quality assessment trials will soon become an important criterion in this field too for customers when decisions are made about awarding contracts.

The EU Water Framework Directive is also one reasons why external quality assessment trials are becoming more important for biological experiments. The Water Framework Directive asserts that any assessment of water must be carried out exclusively on the basis of data of a unified high quality. This is an precedent condition for the objectively and reproducibility assessment of the waterbodies as well as to derive efficient measures.

The proficiency tests at EQAT Phytoplankton

Phytoplankton EQAT (External Quality Assessment Trials) is a joint project organised by the Working Committee of Drinking Water Reservoirs (ATT) and the State Reservoir Administration of Saxony (LTV). The ATT is a non-profit association that involves about 40 water supply companies, water boards, reservoir companies and administrative bodies, universities and inspection and research institutes in Germany and Luxembourg.

The LTV is a state-run company, for which the Saxon Ministry for the Environment and Agriculture is responsible. The LTV operates, administers and monitors the state’s 115 reservoirs and water storage facilities.

The realization of the assessment trials is executed at the examination centre Plauen of the State Reservoir Administration Saxony. The examination centre is accredited according to DIN ISO 17025 and among others also for counting of phytoplankton according to DIN EN 15204.

Planning, realization and assessment of proficiency tests

The provided assessment trials are assessment trials for the quality and suitability check of labs as part of the external quality assurance (proficiency tests).

The assessment trials are based on DIN 38402 - A45, a standard which particularly defines the requirements for the assessment trial organizer as well as for the planning, realization and assessment of those trials. 

The calculation of the target standard deviation and the calculation of the set value are made with procedures of the robust statistics. The assessment of the results of the labs is carried out based on standardized deviations (zu-scores).

 In the case of the assessment of the qualitative taxonomic results the quality target has been set at 80% of the maximum score.

Advisory board

For the development of the assessment trials, their realization and assessment the following persons have been consulted: 

The meetings with Dr. Packroff and Dr. Mehling are organized regularly as part of the meetings of the ATT work group biology. In the forefront of each assessment trial Dr. Jahn and Mr Kusber are involved for the validation of the „taxonomic set values“. The discussion of unclear statistical issues is made situatively with Dr. Uhlig.

Customer satisfaction

The following document enables you to inform us about what you liked at the assessment trial and what we can still do better. We are looking forward to your feedback. 

• Customer Satisfaction Form.pdf

Complaints and appeals

Complaints and appeals against assessment trial results or assessments have to be submitted in a written way to the organizer of the assessment trials within 4 weeks after release of the preliminary results