使用络合显色法测定总磷的含量,在对分光光度计进行调零设置的时候,文献出现以下一段话:In order to remain in the best absorbance zone do not reset to zero with distilled water, but set the deviation of the spectrophotometer galvanometer on a given absorbance for a determined concentration.后面一句是什么意思啊?要对分光光度计电流计做什么操作?