Biochemical alterations in duckweed and algae induced by carrier solvents: Selection of an appropriate solvent in toxicity testing

Carrier solvents are often used in aquatic toxicity testing for test chemicals with hydrophobic properties. However, the knowledge of solvent effects on test organisms remains limited. This study aimed to understand biochemical effects of the four common solvents ((methanol, ethanol, acetone and dimethylsulfoxide (DMSO)) on two test species Lemna minor and Raphidocelis subcapitata by applying Fourier transform infrared spectroscopy (FTIR) coupled with multivariate analysis in order to select appropriate solvents in the toxicity testing. The results showed biochemical variations associated with solvent treatments at different doses on test species. From the obtained infrared spectra, the structures of lipid membrane and protein phosphorylation in the test species were found sensitive to the solvents. Methanol and ethanol mainly affected the protein secondary structure, while acetone and DMSO primarily induced the alterations of carbohydrate and proteins in the test species. The FTIR results demonstrated that methanol and ethanol showed higher biochemical alterations in the test species than acetone and DMSO, especially at the high doses (0.1% and 1% v/v). Based on the growth inhibition and FTIR spectroscopy, acetone and DMSO can be used as carrier solvent in the toxicity testing when their doses are lower than 0.1% v/v. This article is protected by copyright. All rights reserved