Standard solution refers to reagent solution with accurate and known concentration, which is commonly used as titrant in titrimetric analysis. In other analytical methods, use standard solution to draw working curve or as calculation standard.

There are two preparation methods, one is direct method, that is, accurately weigh a certain amount of reference material, dissolve it with appropriate solvent, and then dilute it into a volumetric flask. If the reagent meets the requirements of the reference material (composition is consistent with the chemical formula, high purity, and stable), the standard solution can be directly prepared, that is, an appropriate amount of the reference material can be accurately weighed, dissolved and prepared in a volumetric flask of a certain volume. The weight W of the reference material to be weighed can be calculated by the following formula: W= Μ V · Molar mass of reference material. Where Μ And V are the molar concentration and volume of the solution to be prepared respectively. The above formula can be used to calculate the concentration of standard solution.

The other is the calibration method. Many substances do not meet the conditions of reference materials and are not suitable for directly preparing standard solutions. That is, first prepare the approximate required concentration, and then use the reference substance or the standard solution that has been calibrated by the reference substance to determine the accurate concentration.