GB/T 614-2021 "Chemical Reagent—General Method for the Determination of Refractive Index" is applicable to the determination of liquid organic reagents with a refractive index ranging from 1.3000 to 1.7000. The automatic digital display refractometer method can also be used for dark-colored or translucent samples. The standard specifies the use of an Abbe refractometer (arbitration method) or an automatic digital display refractometer, combined with a constant-temperature water bath and circulation pump with a temperature control accuracy of ±0.1°C. Under the conditions of 20°C and sodium D-line spectral light, the instrument is calibrated, and the refractive angle is measured or the value is directly read. The difference between two measurements should not exceed 0.0002, and the average value is taken as the result to ensure the accuracy of the detection.