Chemicals reagents are commonly referred to as reagent. It is a large class of pure chemical substances with various standard purities and can be used for education, scientific research, analysis and testing as well as the functional materials and raw materials required by some kinds of novel industrial materials. There is a large variety of chemical reagents and the number has reached hundreds of thousands in the world. There are also tens of thousands of reagents that have been used in daily life in china. There is still no uniform international rules in the classification methods for chemicals. It is customary divided by subject and actual application. Take the representative catalog issued by the Germany E • Merck Company as example, there are twelve categories and seventy categories while in most countries, it is divided with the scope of application. We divide the reagents into four categories. 1. General reagents: generally refers to inorganic reagents and organic reagents that can meet standard purity. It is often applied to scientific research, analysis and testing, and synthetic reaction and used as new materials. 2. Analysis Reagents: regent dedicated to analysis and test and can be divided into two subcategories: (1) Reagents for chemical analysis: testing items for the chemical reaction analysis. 1) Baseline Reagent: pure compound directly used for the standard solution in the formulation and volumetric analysis. 2) Indicator: it can be used to indicate the end of the titration reagent and can be classified into pH indicator, redox indicator adsorption indicator, metal indicator, a fluorescent indicator, and so on. (2) Regents for instrument analysis: high-purity compounds dedicated to instrumental analysis. 1) Spectroscopically pure reagents: spectroscopically pure compound, often expressed in the SP for spectral analysis reagents. 2) Chromatography pure reagents: reagents dedicated to analysis of gas chromatography and liquid chrom