Ultrasound-assisted deep eutectic solvent-based liquid-liquid microextraction for simultaneous determination of Ni (II) and Zn (II) in food samples.

A new approach was developed for the simultaneous pre-concentration and determination of Ni (II) and Zn (II) in food samples. This method is based on ultrasound-assisted liquid-liquid micro extraction using hydrophobic deep eutectic solvent (DES) and 1,10-phenanthroline as chelating agent. The effect of several parameters, such as pH, selection and volume of DES, amount of chelating agent, time of sonication and centrifugation, was studied. Under optimized conditions, the developed procedure offered exceptional sensitivity and linearity. The limit of detection was approximately 0.029 µg/Kg and 1.5 µg/Kg for Ni (II) and Zn (II), respectively. The proposed method was applied for the pre-concentration and determination of Ni (II) and Zn (II) in hydrogenated edible oils, fishes, and milk samples. The results of this study were compared with reported methods in the literature revealing its advantages.

5-(5-Bromo-2-meth-oxy-phen-yl)-2-fluoro-pyridine.

In the title compound, C(12)H(9)BrFNO, the dihedral angle between the aromatic rings is 51.39 (5)°; the C atom of the meth-oxy group is close to being coplanar with its attached ring (r.m.s. deviation = 0.0172 Å] and is oriented away from the pyridine ring. In the crystal, mol-ecules inter-act by van der Waals forces.

5-(4-Chloro-phen-yl)-2-fluoro-pyridine.

In the title compound, C(11)H(7)ClFN, the chloro-benzene and 2-fluoro-pyridine rings are oriented at a dihedral angle of 38.83 (5)°. In the crystal, there are no hydrogen-bonding interactions.

2-Fluoro-5-(4-fluoro-phen-yl)pyridine.

In the title compound, C(11)H(7)F(2)N, the fluoro-benzene and the 2-fluoro-pyridine rings are oriented at a dihedral angle of 37.93 (5)°. In the crystal, only van der Waals inter-actions occur.

4-(2-Fluoro-pyridin-5-yl)phenol.

In the title compound, C(11)H(8)FNO, the aromatic rings are oriented at a dihedral angle of 31.93 (6)°. In the crystal, mol-ecules are linked by O-H⋯N hydrogen bonds, forming C(9) chains propagating along the c-axis direction. There are aromatic π-π stacking inter-actions between the pyridine rings [centroid-centroid separation = 3.7238 (16) Å].

5-(2,3-Dichloro-phen-yl)-2-fluoro-pyridine.

In the title compound, C(11)H(6)Cl(2)FN, the dichloro-benzene and the 2-fluoro-pyridine rings are oriented at a dihedral angle of 47.73 (3)°. In the crystal, pairs of C-H⋯N inter-actions link the mol-ecules into dimers with R(2) (2)(12) motifs. Mol-ecules are arranged in stacks extending along [100] via π-π inter-actions with a centroid-centroid distance of 3.8889 (3) Å.