Assessment of the Mutagenicity of Sediments from Yangtze River Estuary Using Salmonella Typhimurium/Microsome Assay
One of the major challenges for mutagenicity assessment of environmental samples and individual compounds for example in the Ames fluctuation test (AFT) is the establishment and control of a well defined exposure concentration. Thus, a combination of passive dosing with silicone O-rings (SRs) together with an analytical confirmation of the freely dissolved concentration (FDC) is presented. FDCs are often determined with a combination of solid phase micro-extraction (SPME) with gas chromatography (GC). For compounds with poor performance in GC, a high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis of bi-distilled water dosed with identically loaded SRs is suggested to avoid interference of the bacterial culture. The approach was tested for six amino-, nitro-, and keto-substituted polycyclic aromatic compounds with a logK(OW) range of 2.5-5.1 without metabolic activation. The method provided reliable concentration-effect relationships and freely dissolved 50% effect concentrations (DEC(50)) 3-33 times lower than nominal effect concentrations (NEC(50)) derived in parallel solvent-dosed AFT. Partition coefficients and NEC(50)/DEC(50) ratios were well correlated with lipophilicity.