Does anyone know of a method for the assay and impurity testing of DMSA (meso-2,3-Dimercaptosuccinic Acid).

Thanks

1. Perform assay by titration against a base.

2. Control the possibility of other optical isomers by measuring oprical otation(OR). For meso isomer OR is zero.

3. To check for other related impurities you can perform GC analysis rather than LC

4. Caution. This sample has a tendency to dimerise or polymerise forming -S-S- link. Even if you allow this sample to mild oxidation like exposure to air, or in a solution containing trace level of dissolved oxygen it is converted to disulphide.