An endpoint detection system for copper stripping using a colorimetric analysis of the change in concentration of a component is described. Wet copper stripping chemicals are used to strip copper from a wafer whereby an eluent is produced. The eluent is continuously analyzed by colorimetric analysis for the presence of copper. The copper stripping process is stopped when the presence of copper is no longer detected. Also novel compounds or chemicals for use in an endpoint detection system for copper stripping using a colorimetric analysis of the change in concentration of the novel compounds or chemicals are described. A composition of matter that serves as an indicator of the presence of copper by colorimetric analysis comprises: 1) Fast Sulphon Black F indicator and an ammonium ion-containing solution or 2) a complexing agent, comprising a diamine, an amine macrocycle, or a monoamine.