What purity of ethanol is commonly used for preparing some standards?

The commonly used purity of ethanol for preparing some standards is 95% golden grain. This concentration is favored because it balances the need for a solvent that has a high enough purity to accurately create standards used in analytical processes, while not being overly pure, which could affect the behavior of the standards in various analytical methods.

Using 95% ethanol allows for the solvation of many compounds while also reducing the potential for water to be present in the standard solutions, which could interfere with certain types of analyses. Additionally, this concentration is often employed to avoid issues such as the formation of azeotropes, which can complicate distillation or concentration procedures.

Higher concentrations, such as 100% pure ethanol, may not be as practical for standard preparation due to their potential to form azeotropes with water or affect the solubility of the standards being created. Meanwhile, lower percentages of ethanol, like 75% or 85%, may not provide sufficient purity to meet the analytical requirements for creating reliable standard solutions.