Ionic liquids as a key medium for efficient extraction of copper complexes from chia seeds (Salvia hispanica L.) Justyna Wojcieszek, Dominik Popowski, Lena Ruzik n Chair of Analytical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Poland article info Article history: Received 30 November 2015 Received in revised form 18 February 2016 Accepted 20 February 2016 Available online 23 February 2016 Keywords: Ionic liquids Chia seeds Inductively coupled plasma-mass spectro- metry Copper complexes abstract Due to insufficient information, the aim of study was to concern on the optimization of extraction procedure of selected metal complexes with flavonoids from chia seeds. Evaluation of the amount of elements in compound, not only their total concentration content, is highly important due to the fact, that only a part from total content of metal is absorbed by human body. At the beginning the total amount of elements in chia seeds was established as 14.51 70.42 mgg 1 for copper, 57.44 71.23 mgg 1 for manganese, 81.12 71.89 mgg 1 for zinc and 0.35 70.13 mgg 1 for cobalt. After the most suitable solvent was established, effects of several parameters on the efficiency of metal extraction were studied. Solvent concentration, solid–solvent ratio, extraction method, extraction time and temperature have been investigated as independent variables. The optimal extraction condi- tions included vortexing during 20 min in 50 °C, using an ionic liquid (1-butyl-3-methylimidazolium bromide) as an extractant, with solid–solvent ratio of 1:20. The determination of total and extractable amount of metals in chia seeds was carried out by standalone ICP MS. In addition, a complementary analysis of extracted metal complexes was performed using SEC-ICP MS method. It was confirmed that the ionic liquid is able to extract different copper complexes in comparison with commonly used sol- vents. The study indicated that extraction by using an ionic liquid has been successfully applied for determination of metals and metal complexes in chia seeds. & 2016 Elsevier B.V. All rights reserved. 1. Introduction Salvia hispanica L., commonly known as chia, is an oilseed plant that was once used by the Aztecs not only as a foodstuff, but also as an offering to the gods. Chia is a natural source of omega-3 (α-li- nolenic acid), fiber (content 430%) and proteins of high biological value. It is a natural source of antioxidants that protect against certain adverse conditions [1], in addition to other important nu- tritional components such as vitamins and minerals [2,3]. Chia can be assigned to “functional food”, apart from the pro- vision of essential nutrition it also has positive effects on human health. It helps, among others, prevent cardiovascular diseases, inflammatory, nervous system disorders and diabetes [4]. In order to fully understand their health benefits it is important to de- termine chemical and physical properties of chia seeds. Therefore, design and improve appropriate equipment to process and pre- pare samples is a key to obtain a good representation of true va- lues from the specimen [2]. Ruiz Medina and co. [5] have reported that the metals con- centration in chia seeds is much higher than in any other in- vestigated food with supposed health benefits (pomegranate, açaí berries, goji berries and mangosteen). For example much higher concentration of calcium and manganese was observed in chia seeds than in goji berries. The quantity of Cu, Fe, K, Mg, P and Zn are similar in goji berries and chia seeds, with differences lower than 4-fold (2-fold in most cases). In addition, chia seeds are rich in natural antioxidants such as tocopherols, phytosterols, carotenoids [6] and phenolic com- pounds, including chlorogenic acid, caffeic acid, myricetin, quer- cetin and kaempherol [2,7]. These compounds protects consumers against many diseases and they also have positive effects on hu- man health. The complexation of metals to flavonoids results in more effective pharmacological activities and better availability of minerals as well as reduces their overloading in body [8]. The scientific literature mostly presents the determination of biological active organic compounds and has focused on food with positive health effects, like açaí, goji berries or chia seeds [9,10]. High percentage of those works involve the determination of phenols and flavonoids, and the evaluation of the antioxidant ac- tivity [11,12]. Only few publications have described the content of metals in some of these fruits [5,13]. Unfortunately, still little is Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/talanta Talanta http://dx.doi.org/10.1016/j.talanta.2016.02.051 0039-9140/& 2016 Elsevier B.V. All rights reserved. n Correspondence to: Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, 00-664 Warsaw, Poland. E-mail address: lenka@ch.pw.edu.pl (L. Ruzik). Talanta 152 (2016) 482–488