Chemical substance made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical. Chemical substances exist as solids, liquids, gases, or plasma, and may change between these phases of matter with changes in temperature or pressure. Chemical substances may be combined or converted to others by means of chemical reactions. Forms of energy, such as light and heat, are not matter, and are thus not "substances" in this
Compound management the storage bank must be monitored for shelf life, quantity, purity and other parameters, and its banked location. In some companies, the compounds can also include biological compounds, such as purified proteins or nucleic acids. The management of these chemical libraries, including renewal of outdated chemicals, databases containing the information, robotics often involved in fetching chemicals, and quality control of the storage environment is called Compound Management or Compound Control. Compound Management is often a significant expense, as well as career for one or more individuals who manage a chemical library at a research site. There are many books and