在吸附溶出伏安法中常用到开路富集,比如 For the preconcentration step, the SiAt-SPCPEwas immersed in a stirred 10mL Ni2+ solution in analytical-grade ethanol, containing a known amount of this metal for a controlled time interval in open circuit potential conditions. 其中in open circuit potential conditions是什么意思,在CHI上如何操作 谢谢