Fig. 1. Schematic diagram of experimental system installation

Fig. 2. Schematic diagram of electrochemical enrichment process

Fig. 3. Intensity of Cd at 228.80 nm before and after polishing of Al electrode

Fig. 4. Intensity of Cd (a) and RSD of single pulses (b) between seven parallel samples

Fig. 5. Spectral intensity of Cd element under different enrichment time

Fig. 6. Spectral intensity of Cd element under different enrichment voltages

Fig. 7. Spectral intensity of Cd element under different KCl concentration

Fig. 8. Schematic diagram of the stability of the polished Al sheet

Fig. 9. Calibration curve of Cd element