Toxicity assessment of a Deep Eutectic Solvent based on Tetra butyl ammonium bromide using Brine Shrimp Lethality Assay

Deep eutectic solvents (DES) have gained popularity recently as a green alternative to the existing solvents. It is essential to evaluate the toxicity of these solvents before considering them ‘green’. This study assesses the effect of a novel DES containing tetrabutyl ammonium bromide and itaconic acid on Brine shrimp nauplii and selected microorganisms. The present study estimated the lethal concentration at which 50 percent of the test population is killed (LC50) using a Brine shrimp lethality assay where brine shrimp nauplii were exposed to 0.01 ppm, 0.03 ppm, 0.05 ppm, 0.1 ppm, 10 ppm, 25 ppm, 50 ppm and 100 ppm concentrations of this DES. A positive control of potassium chromate (1 ppm) and a negative saline control were used for the reference. The calculation of LC50 was done using probit analysis in Microsoft Excel. An attempt has been made to observe the impact of this solvent on the Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and yeast Candida albicans, using the agar cup diffusion method. Chloramphenicol (20 ìg/ ml) and distilled water were positive and negative controls for the antimicrobial and anti-fungal assay. The deep eutectic solvent used in the study did not inhibit the growth of the selected microorganisms. However, the LC50 for this deep eutectic solvent was 9.55 ppm. These results indicate that further studies are required to assess the complete toxicity profile of this deep eutectic solvent.