Abstract: For the prelininary screening of mutagents a novel method was devaloped combining Salmonellamu tag enicity assay with Headspace Gas Chromtography. By monitoring carbon dioxide with gas chromatography, we studied the effect of number of revenants and dose of mutagens on the output of CO₂. An index was selected to assess mutagenicity dose-response relationship. For sodium azide and dexon them in inurn measurable mutagenesis dose were 0. 050 and 0. 080μg/bottle respectively.