One of the most important aspects of analysis is preparing the reagent water used for blanks and reagents. Reagent water is water with no detectable concentration of the compound or element to be analyzed (i.e., it is below the analytical method’s detection level). Reagent water should also be free of substances that interfere with analytical methods. However, its overall quality (concentrations of organic, inorganic, and biological constituents) depends on the water’s intended uses.
Use any method to prepare reagent water that meets the applicable quality requirements. Various combinations of reverse osmosis, distillation, deionization, or ultrafiltration and ultraviolet irradiation can produce reagent water. Keep in mind, however, that improperly operated or maintained water purification systems may add rather than remove contaminants.
This section provides general guidelines for preparing reagent water. Table 1080:1 lists commonly available water purification processes and the major classes of contaminants that they remove. For details on preparing water for microbiological tests, see Section 9020 B.4d.