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In present study, efficiency of three rapid, simple, and reliable sample preparation methods namely dispersive liquid–liquid microextraction (DLLME), air-assisted liquid–liquid microextraction (AALLME), and CO2-assisted liquid–liquid microextraction (CO2-ALLME) have been compared for the extraction and preconcentration of Pt(IV) and Pd(II) ions in environmental water samples prior to flame atomic absorption spectrometry. In this regard, the effect of various experimental parameters on efficiency of the methods like nature and amount of the disperser and extraction solvents, ionic strength, temperature, pH, etc., are investigated to reach high enrichment factors. Due to organic solvent consumption at µL level, all of the studied methods are inexpensive and convenient. The linear ranges of the calibration curves were 10.0–200, 6.0–175, and 6.0–175 μg L−1 for Pd(II), and 20–200, 4.0–200, and 7.0–200 μg L−1 for Pt (IV) ions in DLLME, AALLME, and CO2-ALLME methods, respectively. Extraction recoveries of 81.4, 92.1, and 88.9% for Pd (II) and 85.3, 98.4, and 93.4% for Pt(IV) ions were obtained in DLLME, AALLME, and CO2-ALLME, respectively. Finally, the developed methods were successfully used for the analysis of Pt(IV) and Pd(II) in various water samples. [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]