Separating Phenylboronic acid from its trimer anhydride

[lee]

I am trying to determine the purity of Phenylboronic acid, however, Phenylboronic acid can dehydrate over time to form its cyclic anhydride (AKA Triphenyl boroxin)

I have tried to separate these components by normal phase LC using Partisil 5 column, using Hexane/IPA. I get no separation and both give a v. broad peak with little retention.

Any ideas on what to try next? - i.e change mobile phase/column or try to
derivatise to form a boronate ester.

many thanks in advance

[Bryan Evans]

Below is a chromatogram for aromatic boronic acids separated
on Cadenza CD-C18:

http://www.imtakt.com/TecInfo/TI275E.pdf