Tigriopus fulvus: The interlaboratory comparison of the acute toxicity test.

The paper reports the results of an interlaboratory comparison involving 11 laboratories, with the objectives of apply and validate a new standardized ecotoxicological method on marine crustacean Tigriopus fulvus. Copper was chosen as reference toxicant as indicated in the official method. The results of two independent tests performed by all the participants, demonstrated that the new method is simple, fast and easy to learn. This is confirmed even by the values of z-score index calculated for each laboratory and the relative coefficient of variation (CV) which are 6.32% after 24h, 6.56 after 48h and 35.3% after 96h, mentioned in the ISO standards for the precision of interlaboratory assays. Therefore its use could be recommended in environmental studies and monitoring.

Introduction of oxygenated side chain into imidazolium ionic liquids: evaluation of the effects at different biological organization levels.

The biological effects of a class of oxygenated imidazolium ionic liquids were studied in comparison with alkyl imidazolium salts (BMIM BF4 and BMIM N(CN)2).The cellular and subcellular effects were evaluated on rat pheochromocytoma PC12 cell lines, through MTT test, lactate dehydrogenase release and acetylcholinesterase inhibition; the eco-toxicological responses were assessed through the acute toxicity tests towards Daphnia magna and Vibrio fischeri. The introduction of ethoxy moieties in the lateral chain of imidazolium cations reduced the biological effects in all the tests. The acute toxicity towards D. magna was not affected by the number of ethoxy units, but the crustacean seemed to be sensitive to the type of anion; on the contrary, a further addition of ethoxy moieties increased the toxicity towards V. fischeri, M(OE)4MIM N(CN)2 being the most toxic oxygenated ionic liquid. In the cytotoxicity assays the salts with oxygenated cations resulted ineffective compared to BMIMs, independently from the anion and the number of ethoxy units in the lateral chain. In order to estimate the influence on membrane fluidity, an analysis of fluorescence anisotropy was done and it indicated that BMIM BF4, the most toxic ionic liquid among the tested ones, led to a destabilization of the model membranes at any molarity.