ISO International Standard

ISO 5518:2007 specifies a method for determining the benzoic acid content of fruits, vegetables and derived products.

As chlorobenzoic acids are resistant to oxidation, the method cannot be applied in the presence of p-chlorobenzoic acid, as the absorption spectrum of this acid is close to that of benzoic acid. Neither can it be used in the presence of cinnamic acid, which is transformed into benzoic acid by chromic acid oxidation.