Abstract: An improved low-cost practical method of determining beryllium or a beryllium compound thereof in a sample is disclosed by measuring fluorescence. This method discloses methods to lower the back ground fluorescence. Further, the method is extended to improved analysis of beryllium in soils by including a heating step.

Abstract: An optical media is provided with an associated persistent electrochromic material. The electrochromic material has at least two states. In a first state, the electrochromic material interferes with the ability of an interrogating laser beam to read data from the optical media, and in a second state, the electrochromic material is substantially transparent, enabling the laser beam to read the disc. Advantageously, the persistent electrochromic material holds a desired optical state without the application of external power. The persistent time period may extend for days, weeks, or years depending on particular constructions, and on application requirements. The optical media has an integrated circuit, which is used to cause the electrochromic material to transition from a first state to the second state. In one example, an integrated circuit acts as the powering circuit for the electrochromic material, as well as providing logic and processing functions.