Nitrofurans assay

In order to determine nitrofuran activity in vitro, the minimum inhibitory concentration (MIC) in bacterial cultures must be found by using the serial two fold dilution technique with broth as a medium. Incubation time is 24 hours at 37°C. The cup method, which is usually employed for the assay... 

Several workers " studied the polarographic behaviour of nitrofurans. Nitrofurazone in animal feed has been quantitatively assayed by polaro-graphy. Polarographic assay of nitrofurans will require more basic research before it can be used on a large scale. However, the spectrophotometric assay of nitrofurantoin has been replaced by a polarographic assay in the first U.S. P. XVI supplement (U.S. Pharmacopoeia Convention, 1962). 

The first rec-assay survey on food additives was carried out in 1971 for synthetic dyes, and phloxine (Red Dye No. 104) was found to be positive. The mutagenicity of phloxine was then demonstrated in E. coli WP2 try. AF-2 [2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide], a nitrofuran food preservative, was rec-assayed and found to be a potent mutagen. This substance has been widely used in Japan, and the results initiated a continuing debate on the problem of toxicities due to chemical mutagens. Like other nitrofuran derivatives, AF-2 at first gave negative results with the Ames assay. Positive results appeared later using strains with R plasmid pKMlOl. 

Since chemical analysis of nitrofurans is indispensable their characteristic ultraviolet absorption has been recommended for assay A i. 

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