A single ion exchange bead is ideally suited for the encapsulation of a precisely defined quantity of matter. The amount may well be below the limits of weighability. The ion exchange resin can be prepared under suspension conditions that can yield extremely spherical particles. This geometry permits the weighing of a bead in terms of diameter measurement by using precise microscopic techniques. Microstandard preparation of ion exchange particles is described and is based upon control of the steps of preparation. When the element is radioactive, radioactive beads can be used as point sources that are far more point-like than usually obtained.