European-scale survey on the limit of quantification pratices for priority substances of the water framework directive

The Water Framework Directive defines the chemical status of surface water from monitoring programs concentrations on a list of substances called "priority substances". These concentrations are compared with environmental quality standards (EQS).

Directive 2009/90/EC sets quality assurance and quality control requirements for methods of analysis used within the framework of the monitoring programs and for laboratories that contribute to these programs. In particular, requirements are set for the limit of quantification (LOQ) of the methods. These LOQ shall be less than 30% of the EQS.

For some priority substances, the EQS are so low that LOQ of methods cannot fulfill these requirements. In this case, Directive 2009/90/EC allows the use of best available techniques not entailing excessive costs. In France many questions arise about the level of requirements to be targeted in such cases.

AQUAREF is the French National Reference Laboratory for the monitoring of aquatic environments. It provides support to public authorities for the implementation of the WFD especially on thematic related to quality of data (analysis and sampling methods).

To try to answer some of the questions related to LOQ level, AQUAREF proposed to French public authorities in 2015 to conduct a survey at European level. This survey aims to better know the practices of the other member states. In the future it may help to harmonize practices on this important parameter of the monitoring and assessment of the status of water bodies.

The authors gratefully acknowledge member states who have contributed to this survey: Austria, Belgium, Bulgaria, France, Netherlands, Poland and United Kingdom.