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An analytical approach for the determination of trace amounts of Co(II) and Ni(II) has been proposed using a home-made tablet-based dispersive liquid-liquid microextraction method performed in a narrow-bore tube followed by flame atomic absorption spectrometry. In this method, a mixture of tartaric acid, sodium bicarbonate, and NaCl are used to make the disperser tablet. Then µL-level of an extraction solvent is added on the tablet, and it is released into a narrow-bore tube containing sample solution and a complexing agent. An acid-base reaction between tartaric acid and sodium bicarbonate is immediately occurred, and the produced CO2 leads to dispersion of the extraction solvent as tiny droplets into the solution and subsequent extraction of the analytes. The proposed method made possible the determination of Co(II) and Ni(II) in the ranges of 0.1-15.0 and 0.3-18.0 µg L-1, respectively. Repeatability of the proposed method, expressed as relative standard deviation, was obtained 3.6% and 2.8% (n=6, C=1 µg L-1) for Co(II) and Ni(II), respectively. Relative recoveries (89-97%, obtained at two fortification levels) confirmed the usefulness of the method for analysis of the analytes in the environmental water samples. The method was shown to be fast, reliable, and environmentally friendly with low organic solvent consumption.

A green, simple, rapid, and efficient ligandless air-assisted liquid-liquid microextraction procedure based on solidification of a ternary deep eutectic solvent was developed for the extraction of trace amounts of cadmium(II) and zinc(II) ions in aqueous samples prior to their determination by flame atomic absorption spectrometry. For this purpose, the deep eutectic solvent is formed by mixing sorbitol, menthol, and mandelic acid at a suitable mole ratio and after heating for a short time, a deep eutectic solvent with low density compared to water is synthesised. The synthesised solvent is used as a chelating agent and also as an extraction solvent. Under the optimum experimental conditions, the linear ranges were obtained in the ranges of 0.5–12.5 and 0.5–10.0 µg L−1 for Zn(II) and Cd(II), respectively. The relative standard deviations (n = 6, C = 2.5 µg L−1 of each cation) were 4.2% and 3.4%, for Cd(II) and Zn(II), respectively. Moreover, the obtained detection limits were 0.15 and 0.12 µg L−1 for Cd(II) and Zn(II), respectively. The accuracy of the developed method was studied by analysing SPS-WW2 Batch 108 water as a certified reference material. Finally, the proposed method was successfully applied in the determination of Cd(II) and Zn(II) ions in water and fruit juice samples. Abbreviations: AALLME: Air-assisted liquid-liquid microextraction; ER: Extraction recovery; FAAS: Flame atomic absorption spectrometry; LOD: Limit of detection; LOQ: Limit of quantification; RSD: Relative standard deviation [ABSTRACT FROM AUTHOR]

The impact of rising levels of various heavy metals in the environment from multiple industrial, agriculture, domestic, and technological activities is of great concerns, as heavy metals cause serious health effects for both humans and wildlife. An effective and green chemistry procedure was used for simultaneous extraction of ultra-trace copper and nickel ions in natural waters (e.g. river and well waters) by air assisted liquid-liquid microextraction combined with solidified floating organic drop microextraction (AALLME-SFOD). The extraction of metal ions was conducted in a timescale of several minutes by conversion to metal chelates using sodium diethyldithiocarbamate (DDTC) as a chelating agent prior to AALLME-SFOD procedure, and 1-dodecanol as an extraction solvent to initiate the phase separation of the complex. The response surface methodology (RSM) and central composite design (CCD) were used to optimize the large number of experimental variables (i.e. pH, solvent volume, ligand volume, % NaCl). The analysis of variance (ANOVA) has been applied to evaluate all parameters and their mutual interactions on the extraction yields. The desirability function of Derringer and Suich was applied as a metric for optimization of multiple response variables. The optimized AALLME-SFOD technique proved to be highly effective for the pre-concentration of Cu(II) and Ni(II) from a range of aqueous media (i.e. river and well waters) and provides a quick and easy method, while utilizing compact and low cost equipment with micro-volume organic solvent consumption (e.g. ~120 μL for 5 mL water samples). Quantitation of copper and nickel with Graphite furnace atomic absorption spectroscopy (GFAAS) under the optimum conditions, were linear over the range of (20–100) and (20–200) ng L–1 respectively. Limit of detection for Ni(II) was at 4.5 ng L–1 and 10.4 ng L–1 for Cu(II). [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]

• An efficient reversed-phase DLLME using a synthesized DES is proposed. • The DES was used for the first time as a disperser solvent in RP-DLLME. • It is the first report on the application of the present method in oily samples. A new, sensitive, and safe pretreatment method for the analysis of Cd(II) and Zn(II) ions in oil samples prior to flame atomic absorption spectrometry was developed. For the first time, a deep eutectic solvent is used as a disperser in reversed-phase dispersive liquid-liquid microextraction procedure. For this purpose, a deep eutectic solvent with low viscosity and miscible with both aqueous and organic phases is prepared by mixing glycolic acid and mandelic acid at a molar ratio of 2:1. The variables involved in this process were studied to provide high enrichment factors. Under optimized conditions, the linear ranges of calibration curves for Cd(II) and Zn(II) ions were obtained 0.30−20 and 0.50−30 μg L−1, respectively. The obtained detection limits and enrichment factors were 0.12 and 0.18 μg L−1; and 32.7 and 32.2 for Cd(II) and Zn(II), respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 2.7 to 4.1 % (n = 6, C = 1 μg L−1 of each cation). Finally, the proposed method was successfully applied for the determination of Cd(II) and Zn(II) concentrations in various oil samples. [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]

In this study, a simple and sensitive analytical method was developed for the determination of some heavy metal ions in aqueous samples using inductively coupled plasma-optical emission spectrometry. In this method, firstly, cobalt ferrite nanoparticles were synthesized before they were functionalized with a deep eutectic solvent. The used functionalization solvent was prepared by mixing choline chloride and p -aminophenol. The obtained new nanoadsorbent was used for the extraction of Zn(II), Ni(II), Cu(II), Pb(II), and Hg(II) from the sample solutions by dispersive micro solid phase extraction. The effect of some important parameters such as the sorbent amount, ionic strength, pH, agitation mode and time, and elution solvent type and volume on the extraction efficiency of the method was investigated. Broad linear ranges (1.83–200 ng mL−1) with low limits of detection in the range of 0.54–1.3 ng mL−1 were obtained. The accuracy of the developed method was investigated by determination of the analytes in a certified reference material (SPS-WW2 Batch 108 water). The extraction recoveries of the analytes were obtained in the range of 72–90%. Finally, the developed method was successfully applied to determine the selected ions in different water and fruit juice samples, and the relative recoveries were obtained in the range of 85–104%. • Cobalt ferrite nanoparticles were functionalized with a deep eutectic solvent. • A green solvent instead of toxic and expensive reagents was used for modification. • The sorbent was used for the extraction of Zn, Ni, Cu, Pb, and Hg. • Using low amount of sorbent and low LODs were important features of the method. [ABSTRACT FROM AUTHOR]