This European Standard specifies performance requirements and test methods for the evaluation of procedures for measuring a chemical agent present as a mixture of airborne particles and vapour in workplace air.This European Standard establishes general principles to enable developers and users of mixed-phase samplers and methods to adopt a consistent approach to method validation and provides a framework for the assessment of method performance in accordance with EN 482.Annex A of this European Standard gives guidance on possible approaches to sample mixtures of airborne particles and vapour and Annex B gives information about their physical behaviour.This European Standard is not applicable to methods that differentiate between the sampled airborne particles and vapour.This European Standard is not applicable to a chemical agent present in different chemical and physical forms (for example, mercury in the form of Hg (0) and Hg (II)).