Classification of chemical reagents
Chemical reagents are usually classified according to their purity. Not all chemical analyses require the highest quality and purity. Therefore, reagents are divided into several purity classes. These define the content of the main substances as well as the permissible levels of impurities.
Chemically pure reagents (ch.pr.) – the content of the main substance in the range 99.99-99.999%. These are top-quality reagents, designed to meet the requirements for specialized laboratory techniques. The level of impurities is below the detection limit of chemical methods.
Pure reagents for analysis (prfa.) – the content of the main substance in the range 99.9-99.99%. These are used in laboratories to perform quantitative and qualitative analyses in accordance with norms.
Spectrally pure reagents (spectr.pr.) – the content of the main substance in the range 99.999-99.9999%. These are used for spectral analyses, for example, HPLC, GC.
Pure reagents (pr.) – the content of the main substance in the range 99-99.9%. These have stable quality parameters. They are used in standard laboratory work, usually for qualitative analyses. They can be used as substrates for syntheses and auxiliary substances.
Technical reagents (techn.) – the content of the main substance in the range 90-99%. Usually products of industrial syntheses.
Some chemical reagents are additionally labeled with the FP symbol. Such substances are characterized by extremely high purity. They meet very strict pharmacopeia requirements and are used for pharmaceutical analyses. A similar marking is a PhEur symbol. This symbol confirms that the selected reagent meets the requirements of the European Pharmacopoeia, which means that it can be used for laboratory analyses of medicines in European countries.
Among chemical reagents is also the group of analytical reagents. These are divided into- group, selective, specific, and masking reagents. The classification depends on their application.
Application of chemical reagents
Chemical reagents are most often used in various types of research work, chemical analysis, preparation, and also the production of other substances. The characteristics of laboratory applications and their scale determine the quantities and types of reagents. These substances are used for such analyses as ion determination, separation of cation or anion mixtures, detection of specific ions, and many others.
