Acute toxicity experiment (48h) with Daphnia magna

The concentrations of experimental solution, decided according to the results of a pre-experiment, were set as 5, 10, 15, 20 and 25 mg/L for 4,4’-dihydroxybenzophenone, 0.1, 0.5, 1, 5 and 10 mg/L for 2,4,4’-trihydroxybenzophenone and 0.200, 0.400, 0.600, 0.800 and 1.000 mg/L for 4-MBC. Dimethyl sulfoxide (DSMO) was used as cosolvent. The 40 mL solution were prepared in 100-mL glass beakers. Ten D. magna were added to each beaker. The test lasted for 48 h, during which no feedstuffs were offered. Dead individuals were removed promptly so as not to pollute the water. A blank control group was included and three parallel samples of each group were tested. The numbers of dead D. magna were recorded every 24 h to evaluate the lethal effect of 4,4’-dihydroxybenzophenone, 2,4,4’-trihydroxybenzophenone and 4-MBC on D. magna. The sensitivity of D. magna was tested with potassium dichromate before the experiment. The results met the quality control requirements for D. magna acute toxicity tests [18].