A sampler including an ejector and a sample channel extending to the ejector, which are placeable in a mixture of particles of a solid and a medium, the medium being a gas and/or a liquid. The ejector includes at least one inlet and an outlet. The ejector takes a mixture sample by using vacuum via the inlet and discharges it via the outlet so as to make the mixture sample flow from the inlet towards the outlet. The sample channel takes a desired measuring sample from the mixture sample flowing in the ejector, the solid particles and the medium being at least partly separable from one another in the ejector on the basis of the flow and inertia in the mixture sample.