The protection of waters in Europe is regulated by the Water Framework Directive (WFD), which is mandatory for all European Union members. Significant progress has been made in the use of passive sampling devices for routine monitoring, but some barriers remain that prevent regulatory acceptance of passive sampling devices for checking compliance under the WFD. Adaptation of environmental quality standards suitable for passive sampling devices will allow their use to evaluate the chemical status of waters under the WFD. The main driver of the MONITOOL project is to respond to European Directive demands for the assessment of chemical status of transitional and coastal waters. The quantification of WFD priority substances and emerging contaminants is of capital importance to implement the European policies for the protection of the marine environment. However, in many cases it is very difficult or even impossible, by traditional techniques and there is an urgent need to find accurate, reliable, easy and cost-efficient alternatives. This project is deemed to be very pragmatic by adapting suitable environmental quality standards for priority and specific metals, to allow the use of passive sampling devices in a regulatory context, enhancing the implementation of the WFD and demonstrating the cross-regional (Canaries – Highlands and Islands) applicability of passive sampling devices in water monitoring and assessment by co-deployment of these devices and spot samples.