A QSAR study has been performed using data on the 24-h and 48-h EC50 values for amines to several species of Daphnia. In addition, a QSAR was developed using several species of algae 96-h EC50 data to 18 amines, and provided satisfactory fit to a linear QSAR (EQ 1): log (1/EC50) = 0.49 log P + 0.56 EQ 1 (n = 20; r2 = 0.79; s = 0.53) where P is the n-octanol/water partition coefficient and EC50 is in mmol/L. The data for 48-h EC50 values (EQ 2) to Daphnia gives slightly better fit to the linear QSAR than the 24-h data (EQ 3) for this class of amines, as shown below. log (1/EC50) = 0.52 log P + 0.36 EQ 2 (n = 17; r2 = 0.81; s = 0.56) log (1/EC50) = 0.46 log P + 0.05 EQ 3 (n = 18; r2 = 0.80; s = 0.47)
The amines include both acyclic and cyclic derivatives, either with no additional functional groups, or with the hydroxyl, keto, methoxy, and propargyl moieties. The use of additional molecular descriptors as well as the possibility of more than one molecular mechanism within the study series was investigated.