1,2-Diphenylhydrazine in freshwater and marine water

Toxicant default guideline values for protecting aquatic ecosystems

October 2000

Extracted from Section 8.3.7 ‘Detailed descriptions of chemicals' of the ANZECC & ARMCANZ (2000) guidelines.

The default guideline values (previously known as ‘trigger values’) and associated information in this technical brief should be used in accordance with the detailed guidance provided in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality.

Description of chemical

1,2-Diphenylhydrazine (CAS 122-66-7) is used in organic synthesis and has a major use as a starting material in the manufacture of benzidine. In aerated, aqueous solutions, 1,2-diphenylhydrazine occurs in equilibrium with azobenzene (Griffiths 1972, Rao & Hayon 1976) and the environmental fate of both forms must be considered. According to the octanol-water partition coefficient (log Kow 2.94), both forms should be relatively strongly adsorbed by organic particulates (CCREM 1987).

The only aquatic toxicity data for diphenylhydrazine were for the water flea Daphnia magna, 48-hour EC50 (immobilisation) and LC50, 2180 to 4100 µg/L.

A low reliability freshwater trigger value of 2 µg/L was calculated using an assessment factor (AF) of 1000. This figure was adopted for marine water. Both figures should only be used as an indicative interim working levels.


ANZECC & ARMCANZ 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

CCREM 1987. Canadian Water Quality Guidelines. Canadian Council of Resource and Environment Ministers, Ontario.

Griffiths J 1972. Photochemistry of azobenzene and its derivatives. Chemical Society Reviews 1, 481-493.

Rao PS & Hayon E 1976. Correlation between ionization constants of organic free radicals and electrochemical properties of parent compounds. Analytical Chemistry 48, 564-568.