A chemical is not just a chemical. Chemicals are rated by “grades” which are based on a series of accepted measurements and standards. A chemical’s eventual application determines what grade is called for; the higher the grade required the more difficult a specific chemical is to procure, naturally.
Reagent Reagent chemicals are generally regarded as one of the most high purity chemicals available. Often believed to be synonymous with “ACS” chemicals (those that meet or exceed standards set forth by the American Chemical Society), reagent chemicals are suitable for use in almost any application. For particularly sensitive utilizations such as in a research and development laboratory or analytical situations, reagent-grade chemicals are ideal.
U.S.P. Chemicals in this range meet or exceed the standards set by the United States Pharmacopeia, a non-profit scientific convention whose standards are used in over 140 countries. U.S.P. standards deal primarily with food, drug, and medicinal-grade chemicals and are generally on par with reagent grade chemicals.
Laboratory “Lab grade” chemicals are less pure than reagent chemicals but still relatively pure. Their exact levels of impurities are not necessarily specified, but generally are not excessive. Considered upper-intermediate quality, laboratory grade chemicals are generally acceptable for use in educational laboratories, hence the name.
Pure To be called “pure grade,” a chemical need not even be as technically pure as a lab grade specimen. Also called purified or practical grade, pure grade chemicals are lower-intermediate quality containing an acceptable amount of impurities. These chemicals are not tested to any specific set of standards. Nevertheless, pure grade chemicals are typically suitable for use in general manufacturing or some educational laboratories, depending on the application.
Technical Technical grade chemicals are high enough quality to use industrially, except when a higher purity grade is specified. Often used in large scale commercial manufacturing, technical grade chemicals are not generally suitable for use in applications requiring much lower levels of impurities.
In a perfect world, of course, all chemicals would be the highest-purity. When using reagent grade chemicals is not possible due to cost, availability, or quantity, it’s imperative to understand how differing impurity levels can impact the outcome.