The invention relates to analysis of photon up conversion luminescent inorganic lanthanide-doped nanomaterials and/or separation and/or purification of them from other materials such as biomolecules and/or chemicals used e.g. for bioconjugation in preparation of reagents based on up converting lanthanide nanoparticles for bioanalytical assays. The invention utilizes a high gradient magnetic separator (HGMS) and it can be applied from large submicron materials to small nanoparticles just nanometers or tens of nanometers in diameter. It is also scalable from small analytical scale to preparative scale.