Assessing the mutagenicity of protic ionic liquids using the mini Ames test

Abstract

Background: Protic ionic liquids (PILs) have been suggested as "greener" alternatives to conventional solvents in various industrial applications. In order to assess their suitability for such purposes, a thorough evaluation of their toxicity, mutagenicity, carcinogenicity and environmental impact is crucial. Whilst some studies have been published concerning the biodegradability and toxicity towards microorganisms of a limited number of PILs, no data concerning the mutagenicity of any PIL exist within the literature. As part of our ongoing studies into the toxicity and environmental impact of PILs, we quantify herein the mutagenic potential of a range of PILs through the mini Ames test. Results:In total, 16 PILs and two precursor amines were assessed based on the Ames test, using Salmonella typhimurium strains TA98 and TA100. The 16 PILs used in this study included both carboxylate and chloride anions, as well as secondary and tertiary ammonium cations. Our results show that out of the 16 PILs, 15 gave negative results to the mini Ames test, concluding that they are unlikely to be either mutagenic or carcinogenic. The PIL N,N-Dimethylethanolammonium Octanoate ([DMEtA][Oct]) was toxic to both test strains, and its mutagenic potential could not be assessed by the mini Ames test. The two precursor amines, diethanolamine and N,N-dimethylethanolamine, gave negative results to the mini Ames tests despite the suggestion from other mutagenicity tests of diethanolamine's suggested carcinogenicity.Conclusions: 15 PILs have been deemed likely to be neither mutagenic nor carcinogenic in accordance with the mini Ames test. We find that these results compare well to the relevant carboxylic acids and amines from the literature, suggesting that PILs exist as well solvated ions in these test conditions, similar to those of their precursors in the same test. From this, we caution the use of secondary ammonium cations in PILs, as certain secondary amines have been suggested to be potentially carcinogenic, despite their results from the mini Ames test.

Interactions in Water–Ionic Liquid Mixtures: Comparing Protic and Aprotic Systems

“…The structures of the ILs from our previous work vary both the anion and cation structure, as well as featuring both protic and aprotic ILs. The aprotic cation cholinium ([Ch]) and the protic cation N , N -dimethylethanolammonium ([DMEtA]) are often regarded as being “green” cations due to their favorable biodegradability and low mutagenicity and toxicity. − …”

Cellulose dissolution and regeneration using a non-aqueous, non-stoichiometric protic ionic liquid system

“…The reality of an industrial application of an IL as a solvent for cellulose processing is greatly limited by certain obstacles, typically (1) the number of synthesis steps and ultimately the cost to manufacture the IL (Clark and Tavener 2007;Jessop 2011;George et al 2015), (2) the potential hazards to both operators and the environment posed by the IL such as toxicity, biodegradability and mutagenicity (Docherty et al 2006;Jordan and Gathergood 2015;Reid et al 2015;Clarke et al 2018) and (3) the purification of the IL from its mixtures with other solvents, such as antisolvents used to regenerate cellulose from its solution (Seddon et al 2000). In general, PILs address the first of these points as they can be prepared for much lower costs than AILs due to their straightforward preparation (George et al 2015).…”

Unveiling Noncovalent Interactions in Imidazolium, Pyrrolidinium, or Quaternary Ammonium Cation and Acetate Anion Based Protic Ionic Liquids: Structure and Spectral Characteristics

“…This was also confirmed from the existence of molecular species inferred through 1 H NMR as well as infrared spectroscopy experiments. Likewise, the 15 N NMR experiments on the PILs composed of ammonium and acetate anion by Burrell et al 24 suggested the coexistence of neutral ammonia and ionized ammonium ions which ascertained the proton transfer in these systems. The infrared and NMR spectroscopy thus provide a simple and effective approach to determine the PILs compositions.…”

“…Compilation of experimental data on viscosities, densities, , and ionic conductivities − have proven useful for the rational design of task specific ionic liquids. In particular, the acetate anion based PILs possessing low toxicity, nonmutagenicity, and ready biodegradability find diverse applications such as CO 2 capture, fuel processing, and biomass dissolution . A proton transfer accompanying the PILs has been probed through the 1 H or 15 N NMR, infrared, and Raman spectroscopy experiments. − The synthesis and characterization PIL, triethylammonium acetate, was carried out by Li et al using the total reflectance infrared (ATR-IR) experiments.…”