Experimental design methodology applied to mercury determination: hair samples as a mercury bioindicator.

The application of modified magnetic nanoparticles in extraction of trace Hg was investigated. For this purpose, surfaces of magnetic nanoparticles were modified by 2-picolamine and then utilized as a solid-phase sorbent for Hg(II) extraction. A statistical method, based on surface response design, has been used for the optimization of Hg ion elution from the magnetic nanoparticles. The sorbed Hg ions were eluted quantitatively with 5.5 mL of a solution containing 0.8 M HCl and 0.08 M EDTA after 12 min. The recovery value in this method was 98.6% with RSD of 1.4%, and the obtained LOD was 0.01 ng/mL. The preconcentration factor was calculated to be 179. The method was applied to the determination of hair Hg content for biomonitoring purposes.

Sonoelectrochemical synthesis of a new nano lead(II) complex with quinoline-2-carboxylic acid ligand: a precursor to produce pure phase nano-sized lead(II) oxide.

A new lead complex, [Pb(Q)2] (1) (Q=quinoline-2-carboxylic acid), was prepared via conventional electrochemical method in a fast and facile process and fully characterized by (1)H and (13)C NMR, IR, UV spectroscopies and elemental analysis. The nano-structures of same compound were successfully prepared at 25, 48 and 60°C by a facile and environment-friendly sonoelectrochemical route. The new nano-structure particles were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analysis. Thermal stability of single-crystal and nano-size samples of the prepared compound was studied by thermogravimetric and differential thermal analysis. The effect of sonoelectrochemical temperature on particle size has been investigated, and possible explanations offered. The photoluminescence properties of the nano-structured and crystalline bulk of the prepared complex at room temperature in the solid state have been investigated in detail. The results indicate that the size of the complex particles has an important effect on the optical properties of it. The prepared complexes, as bulk and as nano-particles, were utilized as a precursor for preparation of PbO nanoparticles by direct thermal decomposition at 600°C in air. The nano-structures of PbO were characterized by scanning electron microscopy, X-ray powder diffraction and IR spectroscopy.

Novel Cd(II) ion imprinted polymer coated on multiwall carbon nanotubes as a highly selective sorbent for cadmium determination in food samples.

The application of a novel Cd(II) ion imprinted polymer coated on multiwall carbon nanotubes was investigated for preconcentration and determination of low levels of Cd ions. This novel sorbent was characterized by scanning electron microscopy, thermal gravimetric/differential thermal analysis, elemental analysis, and FTIR spectrometry. Effects of various factors, such as pH of the sample solution, eluent (type, concentration, and volume), and flow rates of the sample and eluent, were evaluated in this study. To investigate the selectivity of the sorbent toward Cd(II) ions, the effects of a variety of ions on preconcentration and recovery of Cd(II) ions were investigated. The LOD was 1.3 ng/mL; the recovery and RSD of the method were 96.4% and below 3.1%, respectively. Validation of the method was performed by analyzing some standard reference materials with certified Cd(II) concentrations. Finally, the sorbent was applied for separation and determination of Cd(II) ions in food samples.

Use of dipyridile amine functionalized magnetic nanoparticles for preconcentration and determination of lead ions in food samples.

Novel dipyridile-modified Fe3O4 nanoparticles were synthesized and characterized by infrared spectroscopy, thermal gravimetric and differential thermal analysis, elemental analysis, high-angle X-ray powder diffraction, and scanning electron microscopy. A novel nano-sorbent was used for rapid extraction, preconcentration and determination of trace amounts of lead(II) ions by flame atomic absorption spectrometry. Various adsorption and desorption parameters were optimized during this study. The optimum conditions were pH 6.0; time of adsorption and desorption at 2 and 5 min, respectively; and a maximum capacity value of 192.6 ± 0.7 mg/g (0.93 mmol/g). The RSD and LOD of the method were 1.43% and 0.7 ng/mL, respectively. The LOQ was 2.4 ng/mL. Standard reference materials of National Institute of Standards and Technology (NIST) 1572 and NIST 1571 were used to verify the accuracy of this method. The sorbent allowed for the successful extraction and determination of low levels of Pb(II) ions in various samples of rice, baking powder, wheat, and other foodstuffs.

Novel ion imprinted polymer magnetic mesoporous silica nano-particles for selective separation and determination of lead ions in food samples.

A novel Pb(II) ion imprinted polymer coated on magnetic mesoporous silica was synthesised and characterised by scanning electron microscopy (SEM), thermal gravimetric/differential thermal analysis (TG/DTA), elemental analysis (CHN) and low angle X-ray powder diffraction (XRD). The application of this sorbent was investigated in preconcentration and determination of low concentrations of lead ions. Through this study, various effective factors on determination, such as pH of the sample solution, eluent including type, concentration and volume, adsorption and desorption time which are effective on the method efficiency, were appraised. In order to investigate the selectivity of this sorbent toward Pb(II) ions, the effect of variety of ions on preconcentration and recovery of Pb(II) ions were also investigated. The limit of detection (LOD) was found to be lower than 1.3 µg L(-1) and the recovery and relative standard deviation (RSD%) of the method were higher than 97.3% and lower than 2.9%, respectively. The application of this sorbent was investigated in separation and determination of lead-contaminated food with concentration below the detection limit of flame atomic adsorption spectroscopy. Validation of the presented method was performed by analysing several standard reference materials with certified lead concentrations.

Determination of polycyclic aromatic hydrocarbons in Persian Gulf and Caspian Sea: gold nanoparticles fiber for a head space solid phase micro extraction.

A gold nanoparticles modified fused silica fiber was developed and used for the head space solid phase micro-extraction (HS-SPME) of polycyclic aromatic hydrocarbons (PAHs), including naphthalene, anthracene, acenaphthylene, phenanthrene, fluoranthene and pyrene. The effects of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength, stirring rate and sample volume were examined and optimized. Linear ranges of 1-300 µg L(-1) for naphthalene, 0.5-250 µg L(-1) for anthracene, acenaphthylene and phenanthrene and 0.05-200 µg L(-1) for fluoranthene and pyrene were obtained. Detection limits were in the range of 10-200 µg L(-1). Single fiber repeatability and fiber to fiber reproducibility were less than 2.5 %-6.0 % and 8.5 %-13.6 %, respectively. Seawater samples were analyzed as real samples and good recoveries (91.9 %-105.3 %) were obtained for target analytes.

Synthesis and characterization of 8-hydroxyquinoline complexes of tin(IV) and their application in organic light emitting diode.

A series of 8-hydroxyquinoline complexes of tin, Q(2)SnCl(2) (Q = 2-methyl-8-hydroxyquinoline, 8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, 5-chloro-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline and 5-nitro-8-hydroxyquinoline) were prepared by reacting stannous dichloride with 8-hydroxyquinoline and its derivatives. All complexes were characterized by elemental analysis, mass spectrometry and infrared, UV-vis and (1)H NMR spectroscopes. Furthermore, the molecular structure of a representative complex, dichlorido-bis(5-nitro-quinolin-8-olato-2N,O)tin(IV), was determined by single-crystal X-ray diffraction. The photoluminescence (PL) properties of all prepared compounds and electroluminescence (EL) property of a selected complex (Q = 5-chloro-8-hydroxyquinoline) were investigated. The results showed that the emission wavelength can be tuned by electron donating or withdrawing group substituent on 8-hydroxyquinoline. Application of prepared complexes in fabrication of an OLED has been demonstrated.

catena-Poly[[(2,9-dimethyl-1,10-phenanthroline-κ(2)N,N')lead(II)]-di-µ-bromido].

In the title compound, [PbBr(2)(C(14)H(12)N(2))](n), the Pb(II) atom lies on a twofold rotation axis. The N-heterocycle-chelated Pb(II) atom exists in a distorted octa-hedral geometry owing to two long Pb⋯Br inter-actions [2.9562 (5) and 3.2594 (5) Å]. These result in a zigzag chain running along the c axis. The lone pair is stereochemically inactive.

2-[(Propan-2-yl-oxy)carbon-yl]quinolin-1-ium tetra-chlorido(quinoline-2-carboxyl-ato-κ(2)N,O)stannate(IV).

In the title salt, (C(13)H(14)NO(2))[Sn(C(10)H(6)NO(2))Cl(4)], the Sn(IV) cation is N,O-chelated by the quinolincarboxyl-ate unit and further coordinated by four Cl(-) anions in a distorted octa-hedral geometry. In the crystal, the 2-[(propan-2-yl-oxy)-carbon-yl]quinolin-1-ium cation is linked to the Sn complex anion by an N-H⋯O hydrogen bond.

8-Hy-droxy-2-methyl-quinolinium tetra-chlorido(quinolin-8-olato-κ(2)N,O)stan-nate(IV).

The reaction of 8-hy-droxy-quinoline, 2-methyl-quinolin-8-ol and stannic chloride yields the protonated 8-hy-droxy-2-methyl-quinolinium species. In the title salt, (C(10)H(10)NO)[Sn(C(9)H(6)NO)Cl(4)], the Sn(IV) cation is N,O-chelated by the quinolin-8-olate anion and is further coordinated by four Cl(-) anions in a distorted cis-SnNOCl(4) octa-hedral geometry. In the crystal, the cation is linked to the anion by an O-H⋯O hydrogen bond.

10-Hy-droxy-benzo[h]quinolin-1-ium tetra-chlorido(pyridine-2-carboxyl-ato-κ(2)N,O)stannate(IV) methanol monosolvate.

The reaction of 4-(dimethyl-amino)-pyridine, picolinic acid and stannic chloride yields the title monosolvated salt, (C(13)H(10)NO)[SnCl(4)(C(6)H(4)NO(2))]·CH(3)OH. The Sn(IV) atom is N,O-chelated by the picolinate ion in a cis-SnNOCl(4) octa-hedral geometry. The cation is linked to the methanol solvent mol-ecule by an O-H⋯O hydrogen bond; the solvent mol-ecule itself is a hydrogen-bond donor to the uncoordinating carboxyl-ate O atom of the anion. The cations and anions are linked by weak N-H⋯Cl inter-actions, forming a chain running along the b axis.

4-(Dimethyl-amino)-pyridinium tetra-chlorido(pyridine-2-carboxyl-ato-κ(2)N,O)stannate(IV).

The reaction of 4-(dimethyl-amino)-pyridine, picolinic acid and stannic chloride yields the title salt, (C(7)H(11)N(2))[SnCl(4)(C(6)H(4)NO(2))], in which the Sn(IV) atom is N,O-chelated by the picolinate ion in a cis-SnNOCl(4) octa-hedral geometry. The cation is linked to the anion by an N-H⋯O hydrogen bond.

[4-(Dimethyl-amino)-pyridine-κN(1)]tri-methyl(thio-cyanato-κN)tin(IV).

In the title monomeric trimethyl-tin(IV) isothio-cyanate-4,4-dimethyl-pyridine adduct, [Sn(CH(3))(3)(NCS)(C(7)H(10)N(2))], the Sn(IV) atom shows a trans-C(3)SnN(2) trigonal bipyramidal coordination. The Sn(IV) atom lies out of the equatorial plane by 0.033 (4) Šin the direction of the donor N atom of the N-heterocycle. The crystal studied was a non-merohedral twin with a minor component of 48.8 (2)%.

A second triclinic polymorph of bis-(µ-N-nitroso-N-phenyl-hydroxy-laminato)-κ(3)O,O':O';κ(3)O':O,O'-bis-[(N-nitroso-N-phenyl-hydroxy-laminato-κ(2)O,O')lead(II)].

The cupferronate ions in the centrosymmetric dinuclear title compound, [Pb(2)(C(6)H(5)N(2)O(2))(4)], O,O'-chelate to the two Pb(II) atoms; two of the four nitroso O atoms are also involved in bridging. The geometries of the five-coordinate Pb(II) atoms in the two independent mol-ecules are Ψ-octa-hedral; if more remote Pb⋯O inter-actions are also considered, the coordination number is increased to six for one mol-ecule and to seven for the other. Their coordination polyhedra are ill defined in the chain motif, which runs along [100].

Dibromido(2,9-dimethyl-1,10-phenanthroline-κ(2)N,N')zinc.

The reaction of equimolar amounts of zinc bromide and 2,9-dimethyl-1,10-phenanthroline in dry methanol provided the title compound, [ZnBr(2)(C(14)H(12)N(2))], in good yield. The Zn(II) ion is coordinated in a distorted tetra-hedral environment by two N atoms from the chelating 2,9-dimethyl-1,10-phenanthroline ligand and two bromide ions. There is inter-molecular π-π stacking between adjacent phenanthroline units, with centroid-centroid distances of 3.594 (3) and 3.652 (3) Å.

Dimeth-yl(1,10-phenanthroline-κ(2) N,N')bis-(thio-cyanato-κN)tin(IV).

The Sn(IV) atom in the title compound, [Sn(CH3)2(NCS)2(C12H8N2)], is located on a twofold rotation axis in a distorted octa-hedral enviroment. The methyl groups are trans to each other [C-Sn-C = 175.7 (3)°], whereas the thio-cyanate groups are cis to each other.

Di-µ2-ethano-lato-octa-methyl-bis-(µ-4-methyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-ido-κ(2) N (1):N (2))di-µ3-oxido-tetra-tin(IV).

The tetra-nuclear title compound, [Sn4(CH3)8(C2H5O)2O2(C3H4N3S)2], lies about a center of inversion; the mol-ecule features a three-rung-staircase Sn4O4 core in which two Sn(IV) atoms are bridged by the 4-methyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-ide group. The negatively charged N atom of the group binds to the terminal Sn(IV) atom at a shorter distance [Sn-N = 2.240 (3) Å] compared with the neutral N atom that binds to the central Sn(IV) atom [Sn← N = 2.641 (3) Å]. The terminal Sn(IV) atom is five-coordinate in a cis-C2SnNO2 trigonal-bipyramidal geometry [C-Sn-C = 127.5 (2)°], whereas the central Sn(IV) atom is six-coordinate in a C2SnNO3 skew-trazepoidal bipyramidal geometry [C-Sn-C = 145.0 (2)°].

Di-µ2-isopropano-lato-octa-methyl-bis-(µ-4-methyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-ido-κ(2) N (1):N (2))di-µ3-oxido-tetra-tin(IV).

The tetra-nuclear title compound, [Sn4(CH3)8(C3H7O)2O2(C3H4N3S)2], lies about a center of inversion; the mol-ecule features a three-rung-staircase Sn4O4 core in which two Sn(IV) atoms are bridged by the 4-methyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-ide group. The negatively charged N atom of the group binds to the terminal Sn(IV) atom at a shorter distance [Sn-N = 2.236 (2) Å] compared with the neutral N atom that binds to the central Sn(IV) atom [Sn← N = 2.805 (2) Å]. The terminal Sn(IV) atom is five-coordinate in a cis-C2SnNO2 trigonal-bipyramidal geometry [C-Sn-C = 136.4 (1)°], whereas the central Sn(IV) atom is six-coordinate in a C2SnNO3 skew-trazepoidal bipyramidal geometry [C-Sn-C = 145.4 (1)°]. The C atoms of the isopropoxy group are disordered over two positions in a 0.591 (7):0.409 (7) ratio.

[µ-1,2,3,4-Tetra-kis(pyridin-4-yl)butane-κ(2) N (1):N (4)]bis-[trimeth-yl(thio-cyanato-κN)tin(IV)].

In the title compound, [Sn2(CH3)6(NCS)2(C24H22N4)], the 1,2,3,4-tetra-kis-(pyridin-4-yl)butane ligand uses the pyridine N atoms at the ends of the butyl chain to coordinate to two trimethylthiocyanatotin(IV) units, forming a dinuclear structure. The Sn(IV) atom in the mol-ecule shows a distorted trans-trigonal-bipyramidal coordination with the methyl groups in equatorial positions. The mol-ecule lies on a center of inversion, with the mid-point of the butyl chain coinciding with this symmetry element. In the crystal, weak C-H⋯π inter-actions occur between pyridine rings of adjacent mol-ecules.

Dimethyl-bis-(2-methyl-quinolin-8-olato-κ(2) N,O)tin(IV).

The Sn(IV) cation in the title compound, [Sn(CH3)2(C10H8NO)2], is N,O-chelated by two 2-methyl-quinolin-8-olate anions and coordinated by two methyl groups in a skew-trapezoidal bipyramidal geometry. In the mol-ecule, the two quinoline ring systems are twisted to one another at 10.91 (18)°. The dimethyl-tin skeleton [C-Sn-C = 149.6 (2)°] is bent over the longer edge of the trapezoid that is defined by the four chelating atoms. Weak inter-molecular C-H⋯O hydrogen bonding occurs in the crystal.