Successive Estimation of Cu, P2O7, and PO4 in Copper Pyrophosphate Plating Solution by Using EDTA

Cu; Titrated with EDTA during warm by using PAN as indicator. P2O7; After Cu was estimated, the solution was adjusted at pH=3.8-4.0 with CH3COOH, and made Zn2P2O7 to precipitate by adding Zn. The precipitate was filtered off, and the excess of Zn++ in the filtrate was titrated with EDTA during warm at pH=10. PO4; After P2O7 was estimated, the solution was added with Mg++ to precipitate MgNH4PO4⋅6H2O. After the precipitate was filtered off, the excess of Mg++ was titrated with EDTA during hot. End point of the titration of P2O7 and PO4 was determined with Cu-PAN indicator. The indicator was the mixture of PAN, added for Cu-estimation, with Cu-EDTA, produced by the titration. In the process of electrolysis, a part of P2O7 was converted into PO4, and some other parts were separated with the electrodeposited copper (its content of P was about 0.09%).