GB/T 20216-2016 "Pulps and paper—Determination of effective residual ink concentration (ERIC value)—Infrared reflectance measurement" specifies the method for determining the effective residual ink concentration (ERIC value) in pulps and paper using infrared reflectance measurement, applicable to various types of pulps and paper. Samples are collected according to GB/T 450 and prepared according to GB/T 8940.2. Reflectance is measured using an infrared reflectometer at specific wavelengths, and the ERIC value is calculated based on a standard curve. The method is modified from ISO 22754:2008, referencing standards such as GB/T 22903 and GB/T 7973, with certain provisions from the international standard omitted to ensure the determination meets domestic application requirements.