Azobenzenes, contaminants

Occasionally the product is contaminated with an impurity (1-2%), which appears as tiny red needles. This material has been tentatively identified as diethyl azobenzene-4,4 -dicarboxylate [Benzoic acid, 4,4 -azobis-, diethyl ester],... 

Hall et al. (1985) reported that no 1,2-diphenylhydrazine (less than pg/L) was detected in the Nanticoke River near the Chesapeake Bay. The analytical method involved liquid-liquid extraction, concentration, and. analysis by GC/MS. The Contract Laboratory Program statistical database (queried April 13, 1987) reported that 1 2-diphenylhydrazine has been detected n water at i of 357 hazardous waste sites at a concentration of (96 ppb (CLPSDB 1987), and has been reported at 7 of 117, sites. n the national Priority List database (ATSDR 1990) The U.S. EPA Contract laboratory Program uses GC methods to analyze the contaminants of interest. Since 1,2-diphenylhydrazine oxidize, to azobenzene in the GC injector port and both 1,2-diphenylhydrazine and azobenzene, have the same GC retention time and mass spectra, reports of 1,2-diphenylhydrazine from the Contract Laboratory Program may actually represent detections of 1,2-diphenylhydrazine, azobenzene, or both (see Chapter 6 for more details). 

The azo compound, 3,3, 4,4 -tetrachloroazobenzene, bears a steric resemblance to TCDD. It induces aryl hydrocarbon hydrolase activity in mice and chick embryos. It may be acnegenic and it is a potential carcinogen (19). It has been detected as a contaminant in formulations of the herbicide, propanil (3,4-dichloropropionanilide). Azobenzenes have also been detected in commercial samples of the urea... 

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