A New Method for Determination of Purity of 3,3′,4,4′-Biphenyl-tetracarboxylic Dianhydride

It was shown that in HPLC analysis,3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA in short) was hardly to be separated from the by-product 3,3′,4,4′-biphenyltetracarboxylic acid (BPTA in short),and in addition,some more BPTA was produced by hydrolysis of BPDA with the mobile phase when passing through the chromatographic column.Hence,results with significant errors were obtained by determination of purity of BPDA by HPLC.It was proposed that the purity of BPDA can be determined by alkalimetric titration of products of alcoholysis and hydrolysis of BPDA with NaOH standard solution separately,and the content of BPDA (i.e.,its purity) calculated from the difference of volume of the titrant used as shown by the given formula.The presence of the impurity,BPTA,did not interfere with the determination.In the analysis of a sample of BPDA having its purity of 99.58%,the value of relative deviation found was 0.29%.