Abstract: Fat-free cotton copper separation was the term firstly proposed by us in this paper. it was successfully applied in sodium diethydithiocarbamate extraction spectrophotometric determination of copper with advantages such as:simple to dewater process, less consumption of extraction -solvent realization of solvent extraction only once, not fwice ormore improvement both in accuracy and reliability, less enviromental pollution, ect, It was considered to be applicable to certain other extraction spectrophotometric determinations with similar advantages.

Key words: Fat-free cotton separation Method of extraction spectrophotomeric determinatio Copper.