Influence of cosolvents on low water-solubility chemicals to Photobacterium phosphoreum in acute toxicity test

There is little information about the influence of organic solvents for low water-solubility compounds on Photobacterium phosphoreum toxicity test, though it appears likely that much of data were obtained by using solutions prepared with the cosolvents or surfactants. In this study the influence of five stock solvents, including dimethyl sulphoxide (DMSO), acetone, aether, ethanol, tetrahydrofuran, on Photobacterium phosphoreum toxicity test were measured and different effective concentration (EC) values were obtained. DMSO was selected as the most suitable solvent of chemical compounds with low water-solubility according to its good characters and less toxicity effect to Photobacterium phospherum. Chlorobenzene and nitrobenzene, whose toxicity can be detected even if without any solvent, were selected to testify the effect of DMSO to toxicity of chemicals to Photobacterium phopherum. It was demonstrated that DMSO (its concentration no more than 0.20mol.L-1) had little effect on the toxicity of organic chemicals with EC value no more than 10%. The successful application of DMSO used as cosolvent provides a good example and a good idea to improve traditional acute toxicity test of Photobacterium phopherum.