Primary standards is of high purity, less impurity, good stability, chemical composition constant. Capacity analysis, the reference reagent in determination of pH in determination of calorific value, and so on. Have the first reference and classification standard of each classification. Where the first reference must be made by the National Institute of metrology verification. The production units used as the first reference standard benchmark products. At present, reference reagent business mainly refers to the capacity analysis in capacity analysis of benchmark [content range 99.95%~100.05% (gravimetric titration). Generally used to calibrate the titrant.
Chemical reagents are often spoiled by improper storage in storage. Some easy moisture absorption and deliquescence or hydrolysis reagent; some easily with oxygen in the air, carbon dioxide or other gases in the diffusion reaction, and some reagents affected by light and temperature will deteriorate. Therefore, according to the different properties of reagents, appropriate measures should be taken to properly preserve them.