were developed for use as reference or calibration materials and in applications where a high visual contrast is desired. The product line consists of uniform particle sizes between 50 and 500 microns in either red or black color. The microspheres are made from cross-linked polystyrene divinylbenzene (PSDVB) copolymer and can be stored at room temperature. They can be dispersed in aqueous media with the aid of a small amount of surfactant, or in lower alcohols, such as methanol and ethanol. Some dye extraction will result when the particles are suspended in pure alcohols, but will be minimal. Other organic solvents, such as ethers or chlorinated hydrocarbons, should be avoided because they will swell the particles and completely extract the dye. Chromosphere T product include a Certificate of Calbration and Traceability. Typical applications include: • Reference or calibration materials • Testing of filtration media and systems • Vial and container cleaning evaluations • Flow tracing and fluid mechanics • Contamination control • Sedimentation processes • Calibration of injection devices • Pharmaceutical manufacturing control