This document specifies the requirements for the sampling and processing of complex matrices in order to obtain a liquid dispersion having a sufficiently high concentration of nano-objects of interest. This document provides guidelines for the detection and identification of specific nano-objects in complex matrices, such as liquid environmental compartments, wastewater, and consumer goods (e.g. food and cosmetics). For identification, this document requires prior knowledge of the nature of the nano-objects, such as their chemical composition. The detection and identification methods chosen are based on a combination of size classification and chemical composition analysis. Characterization of morphology can, for example, also support identification. At present, only the techniques of field flow fractionation (FFF), electron microscopy (ME) and inductively coupled plasma mass spectroscopy (spICP-MS) fulfill this combination requirement.