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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]

• Presenting a new microextraction procedure combined with GC–MS for the analysis of several aliphatic amines from urine samples. • A continuous homogenous liquid phase microextraction based on in situ preparation of 4-chlorophenol: choline chloride deep eutectic solvent is proposed. • The deep eutectic solvent is prepared in solution by passing the solution containing the related compounds from a syringe barrel filled with exothermic salts. • The enrichment factors were in the range of 188–246 and the limits of detection and quantification were 0.16–0.37 and 0.56–1.25 ng mL−1, respectively. • The results showed that the method is a rapid, simple, cost effective, and eco-friendliness sample preparation technique. In the present work, a new microextraction procedure combined with gas chromatography-mass spectrometry has been developed for the analysis of several aliphatic amines from urine sample. The sample preparation method was a continuous homogenous liquid phase microextraction that was based on in-situ preparation of 4-chlorophenol: choline chloride deep eutectic solvent. The deep eutectic solvent was prepared by passing the mixture of related compounds through a syringe barrel filled with exothermic salts (calcium chloride and potassium bromide). The released heat by dissolving the salts and increasing the solution ionic strength assists the formation of the deep eutectic solvent. The influence of various factors on the efficiency of the proposed procedure including salts amount, flow rate, pH, salting-out effect, and extraction solvent volume was studied. The calibration curves were linear broadly over the concentration range of 1.2–250 ng mL−1 with coefficient of determinations ≥0.996. The enrichment factors were in the range of 188–246 and the limits of detection and quantification were 0.16–0.37 and 0.56–1.2 ng mL−1, respectively. Based on the results, the offered method was sensitive, rapid, eco-friendly, and efficient for extracting and determining aliphatic amines in urine samples. [ABSTRACT FROM AUTHOR]

The presence of heavy metals in crude oil can create different problems on the oil processing and devices as well as pollution of the environment. Establishment of sample preparation methods for the extraction of metals from crude oil is the bottleneck of a successful determination method due to high hydrophobicity and complexity of crude oil matrix. In this study, a dispersive solid phase extraction procedure was developed for the simultaneous extraction of sixteen metal ions based on in-situ formation of an adsorbent in the sample solution. For this purpose, a suitable amount of dithiooxamide was dissolved in an organic solvent and was injected into the sample solution. By this action, dithiooxamide was re-precipitated in the sample solution and adsorbed the ions. The solid particles were separated and then the ions were eluted by a few microliters of choline chloride: 5-amino-8-hydroxyquinoline deep eutectic solvent under sonication. The presented method was validated and broad linear ranges (7.56–50000 ng g−1) were obtained for calibration curves with coefficient of determination ≥0.992. Acceptable limits of detection (0.003–2.32 ng g−1) and quantification (0.009–7.56 ng g−1) were achieved. Good precision (relative standard deviation less than or equal to 4.3% for intra and inter-day precisions) and acceptable extraction recoveries (66–91%) were also obtained. Seven crude oil samples were analyzed and ten metal ions were determined successfully. The method was compared with the methods reported in literature and it was found that the data obtained by this method were reliable and accurate. [Display omitted] • In-situ formation of a solid adsorbent was used for the extraction of some metal ions from crude oil. • Microflow nebulizer inductively coupled plasma-mass spectrometry was used for determination of the analytes. • Choline chloride: 5-amino-8-hydroxyquinoline deep eutectic solvent was used during extraction procedure. • Greenness, low cost, and effective sample preparation are advantages of the method. [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]