After the rice sample is dried and ashed, it is sent to an electric evaporator for heating, evaporating out atomic cadmium, and generating atomic fluorescence under the excitation of the emitted light of a cadmium hollow cathode lamp. The intensity is proportional to the mass of cadmium in the sample. The corresponding cadmium mass is found from the calibration curve and the cadmium content in the sample is calculated. Based on the above principles, Appendix A mainly introduces an online atomic capture technology, which can be used in conjunction with solid sample electrothermal evaporation atomic fluorescence to significantly reduce the matrix interference.