Cupferron

Cupferron (ammonium N-nitroso-N-phenylhydroxylamine) was synthesized in 1907 by Baudisch and introduced as an analytical reagent that forms precipitates with ferric iron, copper, titanium, and other metal ions — hence 'cupferron' (copper-iron) [1]. It became a standard reagent in classical wet chemical analysis and trace metal analytical chemistry [2]. With modern instrumental methods replacing classical gravimetric analysis, cupferron use has declined, but it remains used in some separation chemistry and extraction procedures [1]. OSHA regulates it as a carcinogen under 29 CFR 1910.1003-1016 [2].

Laboratory chemists performing classical wet chemical analysis and metal extraction chemistry [1]. Research chemists using cupferron for metal ion separation [2].

Cupferron undergoes metabolic reduction to phenylhydroxylamine and then N-hydroxylation, generating reactive intermediates that form DNA adducts and cause liver, kidney, and forestomach tumors in rodents [1]. It is also a methemoglobin-former via direct oxidation of hemoglobin iron [2]. EPA Group B2 probable carcinogen; OSHA regulated carcinogen [1].

Analytical laboratory chemists [1].

1. All cupferron handling must occur in a certified fume hood [1]. 2. Use modern alternative analytical methods (ICP-MS, AAS) in place of classical cupferron precipitation wherever possible [2]. 3. OSHA medical surveillance required for regularly exposed workers [1].