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A simple, efficient, green, and organic solventless dispersive liquid–liquid microextraction procedure was developed to determine Co(II) and Ni(II) ions in water and fruit juice samples by flame atomic absorption spectrometry. In this study, for the first time, both of dispersive and extraction solvents of the method are deep eutectic solvents. Therefore, it is performed without using any organic solvent. The dispersive solvent is composed of choline chloride and butyric acid at a molar ratio of 1:2. The solvent prepared from a mixture of choline chloride and phenylacetic acid at a molar ratio of 1:2 is acted as an extraction solvent. Effect of various analytical parameters such as constituents and molar ratios of dispersive and extraction solvents, volume of the synthesized solvents, temperature, ionic strength, and pH of sample solution on extraction efficiency of the method were investigated and optimized. After optimization of the method, good linearity in the ranges of 0.29–40 μg L−1 and 0.5–40 μg L−1 with coefficients of determination of 0.9919 and 0.9976 was obtained for Co(II) and Ni(II), respectively. Low limits of detection were obtained for Co(II) and Ni(II) (0.10 and 0.17 μg L−1, respectively). The extraction recoveries of the analytes were 95.4% and 92.8% for Co(II) and Ni(II), respectively. To investigate validity of the method, SPS-WW2 as a certificate reference material was analyzed with the proposed method. Finally, the method was successfully applied to determine Co(II) and Ni(II) ions in different water and fruit juice samples. [ABSTRACT FROM AUTHOR]

A vortex‐assisted dispersive micro‐solid‐phase extraction procedure using a new and green sorbent was developed as a simple, fast, and efficient sample preparation method for the extracting five pesticides in several fruit juice samples. In this study, for the first time, riboflavin was used as an efficient sorbent. A few milligrams of riboflavin was directly added into the aqueous solution containing the analytes to adsorb them. After adsorption the analytes, they were desorbed and more concentrated by a dispersive liquid–liquid microextraction procedure. The influence of several effective parameters such as amount of riboflavin, pH, vortex time, eluent nature and volume, and extraction solvent type and volume on the extraction efficiency was investigated. In optimal conditions, linear ranges of the calibration curves were broad. The limits of detection and quantification were attained in the ranges of 0.56–1.5 and 1.9–0.52 ng mL−1, respectively. The proposed method demonstrated to be suitable for concurrent extraction of the studied pesticides in various fruit juice samples with high enrichment factors (320–360) and precision (relative standard deviation ≤7.8% for intra‐ [n = 6] and interday [n = 4] precisions at a concentration of 25 ng mL−1 of each pesticide). [ABSTRACT FROM AUTHOR]

A green and efficient dispersive liquid-liquid microextraction method based on a new deep eutectic solvent has been developed for the preconcentration and extraction of cobalt and nickel ions. The deep eutectic solvent is formed by mixing choline chloride (hydrogen bond acceptor) and 4-aminophenol (hydrogen bond donor). Then, it is used as a chelating agent as well as extraction solvent. Under the optimum experimental conditions, the linear ranges for Ni(II) and Co(II) were 0.80–50 and 0.50–50 µgL−1, respectively, by flame atomic absorption spectrometry. The obtained detection limits were 0.30 and 0.22 µg L−1 for Ni(II) and Co(II), respectively. ChCl: choline chloride; DES: deep eutectic solvent; DLLME: dispersive liquid-liquid microextraction; EF: enrichment factor; ER: extraction recovery; FAAS: flame atomic absorption spectrometry; LOD: limit of detection; LOQ: limit of quantification. [ABSTRACT FROM AUTHOR]

A simple, green, rapid, and efficient ligandless dispersive liquid-liquid microextraction procedure based on solidification of a ternary deep eutectic solvent has been proposed for the extraction of trace amounts of Cd(II), Cu(II), and Pb(II) ions in milk samples prior to their determination by flame atomic absorption spectrometry. Initially, a suitable mole ratio of sorbitol, menthol, and mandelic acid are mixed in a test tube, and after heating, a deep eutectic solvent with low density compared to water is formed. The synthesized solvent is used as a chelating agent and an extraction solvent in the extraction of some heavy metal ions from milk samples. The influence of several effective parameters on the responses and extraction recoveries of the analytes was investigated. Under the optimum experimental conditions, the linear ranges were in the ranges of 1.0–40 μg L−1 for Cd(II) and Pb(II), and 1.0–25 μg L−1 for Cu(II). The obtained relative standard deviations (n = 6, C = 2.5 μg L−1 of each cation) and detection limits were in the ranges of 3.4–4.1% and 0.38–0.42 μg L−1, respectively. Finally, the developed method was successfully applied for the determination of Cd(II), Cu(II), and Pb(II) ions in different milk samples. Image 1 • An efficient ligandless DLLME method using a synthesized ternary DES is proposed for the extraction and preconcentration of Cd(II), Cu(II), and Pb(II) ions at trace levels from milk samples. • A few microliters of the synthesized DES was used simultaneously as a complexing agent and an extraction solvent, therefore, the extraction was performed without using any organic solvent. • This study is the first report on the application of the present method for the extraction of heavy metals in milk samples. • The proposed method offers numerous advantages, such as simplicity, ease of operation, and low cost. • The developed method was used for the determination of the analytes in different milk samples. [ABSTRACT FROM AUTHOR]