Properties of the Isochromatic Dye IonPairs Formed by Bromophenol Blue and Butylrhodamine B

The properties of bromophenol(BPB) and butylrhodamine(BRB) and the isochromatic dye ionpairs formed by BPB and BRB were studied. The experiment showed that the proportion of BPB∶BRB was 1∶3 at pH 7, K sp =2.66×10 -23 and the extraction rate was 94.9%. The absorption was proportional to BPB concentration over the range of 0～6×10 -6 mol/L. It is the foundation of application of BPB and BRB in extraction spectrophotometry.