a method for producing silicate - containing magnetic particles having a closed and tight silicate layer and high purity . in addition , the novel method prevents an uncontrolled formation of aggregates and clusters of silicates on the magnetite surface , thereby having a positive influence on the properties and biological applications . the method enables depletion of nanoparticulate solid substance particles on the basis of a fractionated centrifugation . the silicate - coated magnetic particles exhibit optimized magnetization and suspension behavior as well as advantageous run - off behavior from plastic surfaces . these highly pure magnetic particles coated with silicon dioxide are preferably used for isolating nucleic acids from cell and tissue samples , whereby the separating out from a sample matrix ensues by means of magnetic fields . the particles are particularly well suited for the automatic purification of nucleic acids , mostly from biological body samples for the purpose of analyzing them with different amplification methods .