I have found that suppliers list a NaOH titration to test this material. I've tried several times without success, or low purity values with a very weak equivalence. NMR indicates the material is good. I also tried non-aqueous HClO4 despite the likelihood of removing the boc protecting group. For the aqueous titration, it seems that the unprotected amine would be expected to cause real problems, especially since the material salts with itself. Does anyone know if there is more to this titration?