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A limitation of the microtox® test for toxicity measurements of nonionic surfactants
Author(s) -
Sherrard Kim B.,
Marriott Philip J.,
McCormick Malcolm J.,
Millington Keith
Publication year - 1996
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620150703
Subject(s) - toxicity , pulmonary surfactant , ec50 , dilution , surface tension , critical micelle concentration , nonionic surfactant , chemistry , chromatography , micelle , environmental chemistry , organic chemistry , aqueous solution , thermodynamics , biochemistry , physics , in vitro
The Microtox® test was successfully used to measure EC50 values of nonionic polyethoxylate surfactants. However, toxicity measurements of real samples that contain surfactants above a particular concentration, termed the critical toxicity concentration (CTC) are not valid. These samples require dilution before the test is performed, and because the relationship between toxicity and concentration is not linear above the CTC, the EC50 cannot be extrapolated back to give the toxicity of the original concentrated sample and a true estimation of toxicity is therefore not possible. This phenomenon may be related to the minimum surface tension requirement of the bacteria or other physical properties of the surfactant such as the tendency to assemble at interfaces and surfaces and the tendency to form micelles.