An analysis was needed which would indicate the purity and acid content of maleic anhydride. Small amounts of acid can affect the copolymerization behavior of the anhydride 1] and may cause rearrangement and polymerization of the diene component in Diels-Alder reactions 2]. Standardized solutions of tertiary amines such as tripropylamine and N-ethylpiperidine have been used by Siggia and Floramo 1] to titrate maleic and phthalic acids in their anhydrides. This method is rather specific for maleic acid since the acids which might be included in the determination are those with dissociation...