New solvents for metal extraction – NADES. Prediction and optimization of efficient extraction of selected metals by ICP-MS/MS

The purpose of this work was the optimization of selected metal extraction efficiency from barley grass (Hordeum vulgare L.). Firstly, the extraction of metal complexes from a plant, with a system in which natural deep eutectic solvents (NADES) play the role of an extractant, was referenced. The prediction, employing computational research – the COSMO-RS (COnductor like Screening MOdel for Real Solvents) model, was carried out. Secondly, after the selection of nine different types of natural deep eutectic solvents, the extraction procedure was elaborated taking into account the total concentration of four metals: manganese, copper, zinc, and molybdenum in powdered barley grass samples. During the optimization of the extraction process, three parameters were checked: time, temperature and water quantity in the NADES composition. Due to the changes in the viscosity and density of NADES, the mentioned factors crucially influence the efficiency of analytes transferring to the extractant. In order to determine the total amount of extracted metals, inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was employed. The accuracy of the established methodology was tested using a certified reference material (CRM). The obtained results confirmed the adequacy of NADES utilization for effective extraction of metals from plants and can be treated as a premise for the future application of these extractants in speciation analysis of metals.