Different Lubricating Oil Treatments for the Determination of Cu,Cr, Fe,Ni, Sb,Pb, and Zn by HR-CS FAAS

Abstract

Microwave-assisted acid decomposition, direct dilution in kerosene, and oil-in-water emulsion were evaluated as lubricating oil pretreatment procedures for Cu, Cr, Fe, Ni, Pb, Sb, and Zn determination by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). For wet digestion, results were compared with those obtained by Flame Atomic Absorption Spectrometry (FAAS). The ultrasound probe used in emulsions sonication contaminated samples with Cr, although better results have been observed for the other six elements in this condition. In general, recovery percentages ranging from 81–106% (Cu), 80–107% (Cr), 85–114% (Fe), 82–116% (Ni), 86–117% (Pb), 85–115% (Sb), and 81–114% (Zn) were obtained. The HR-CS FAAS showed to be faster and more sensitive than FAAS.     

Sorption of methane,ethane, propane,butane, carbon dioxide,and nitrogen on kerogen

Sorption isotherms of nitrogen, methane (in the pressure range of 0.1–40 MPa), ethane (0.1–3.7MPa), propane (0.01–1 MPa), butane (0.01–0.2 MPa), and carbon dioxide (0.1–6 MPa) are measured on two adsorbents with kerogen contents of 16 and 75% at temperatures of 303, 323, 343 K. Adsorption volumes are calculated for all adsorption systems using two independent methods. The BET technique is used to determine the surface area values of the two adsorbents on the basis of sorption data for ethane, propane, butane, and carbon dioxide. The initial and isosteric adheat of sorption values are calculated on the basis of sorption isotherms of ethane, propane, butane, carbon dioxide measured at three temperatures. It is found from comparing the dependences of isosteric heat of sorption on the two adsorbents that molecules of the above gases diffuse into its bulk (adsorbent 2) in addition to sorbing on the outside surface formed by kerogen molecules, while sorption of the same gases on the rock (adsorbent 1) is similar to sorption on a smooth hard adsorbent surface.     

Comparison of membrane assisted solvent extraction,stir bar sorptive extraction,and solid phase microextraction in analysis of tetramine in food

Three environmentally friendly extraction techniques, membrane assisted solvent extraction (MASE), stir bar sorptive extraction (SBSE), and headspace solid phase microextraction (HS‐SPME), were compared for the direct analysis of the highly toxic rodenticide tetramine in food. The optimized MASE method was applied to seven foods fortified with tetramine and compared to previously reported SBSE and HS‐SPME results. Parameters such as the standard addition linearity (MASE (0.964–0.999), SBSE (0.966–0.999), HS‐SPME (0.955–0.999)), recovery (MASE (12–86%), SBSE (36–130%), HS‐SPME (50–200%)), reproducibility (MASE (3.0–30%), SBSE (4.4–9.6%), HS‐SPME (1–12%)), and LOD (MASE (1.6–6.4 ng/g), SBSE (0.2–2.1 ng/g), HS‐SPME (0.9–4.3 ng/g)) were compared.     

Simultaneous determination of praziquantel,pyrantel embonate,febantel and its active metabolites,oxfendazole and fenbendazole,in dog plasma by liquid chromatography/mass spectrometry

A liquid chromatography–electrospray–mass spectrometry method (LC/MS) has been developed and validated for determination of praziquantel (PZQ), pyrantel (PYR), febantel (FBT), and the active metabolites fenbendazole (FEN) and oxfendazole (OXF), in dog plasma, using mebendazole as internal standard (IS). The method consists of solid‐phase extractions on Strata‐X polymeric cartridges. Chromatographic separation was carried out on a Phenomenex Gemini C₆‐Phenyl column using binary gradient elution containing methanol and 50 mm ammonium–formate (pH 3). The method was linear (r² ≥ 0.990) over concentration ranges of 3–250 ng/mL for PYR andFEB, 5–250 ng/mL for OXF and FEN, and 24–1000 ng/mL for PZQ. The mean precisions were 1.3–10.6% (within‐run) and 2.5–9.1% (between‐run), and mean accuracies were 90.7–109.4% (within‐run) and 91.6–108.2% (between‐run). The relative standard deviations (RSD) were <9.1%. The mean recoveries of five targeted compounds from dog plasma ranged from 77 to 94%.The new LC/MS method described herein was fully validated and successfully applied to the bioequivalence studies of different anthelmintic formulations such as tablets containing PZQ, PYR embonate and FBT in dogs after oral administration. Copyright © 2015 John Wiley & Sons, Ltd.     

A u.v.-absorptiostat and its applications: Determination of catalase,ascorbate oxidase,peroxidase, sorbitol dehydrogenase and lactate dehydrogenase

The instrumental set-up and applications of a u.v.-absorptiostat are described. It is used to determine enzymes such as catalase (1.5–15 U), ascorbate oxidase (3–30 mU), peroxidase (10–100 mU), sorbitol dehydrogenase (15–150 mU) and lactate dehydrogenase (15–150 mU). It is also shown that this method is of special interest for the determination of enzymes with low substrate concentrations.     

Conformational Heterogeneity in Diphthalocyaninato(2–)metallates(III) of Sc,Y, In,Sb, Bi,La, Ce,Pr, and Sm

Potassium diphthalocyaninato(2–)metallate(III), K[M(pc^2–)₂] (M = Bi, La, Ce, Pr, Sm, Sb, In) has been prepared by melting the metal chloride, iodide or acetate with 1,2‐dicyanobenzene in the presence of potassium methylate. Crystallisation with tetra(n‐butyl)ammonium bromide or hydroxide ((ⁿBu₄N)Br/OH), tetra(n‐pentyl)ammonium chloride ((ⁿPe₄N)Cl) or bis(triphenylphosphine)iminium halide ((PNP)X; X = Br, I) yields the corresponding red‐purple complex salt (ⁿBu₄N)[M(pc^2–)₂] (M = Bi ( 1 ), La ( 3 ), Ce ( 2 )), (ⁿBu₄N)[M(pc^2–)₂] · x CH₃OH (M = Bi ( 5 ), Pr ( 6 ), Sm ( 7 ); 0 9 x 9 1), (ⁿPe₄N)[La(pc^2–)₂] ( 4 ), (ⁿBu₄N)[Pr(pc^2–)₂] · 2 py ( 10 ), (ⁿBu₄N)[Sb(pc^2–)₂] · 2 thf ( 11 ), (PNP)₂[M(pc^2–)₂]Br · 2 Et₂O (M = Sb ( 12 ), Bi ( 13 )), and (PNP)₂[In(pc^2–)₂]I · 2 Et₂O ( 14 ). Bronze coloured diphthalocyaninato(1–)metal(III) polyiodide, [M(pc^–)₂]I₂ (M = Sc, Y) has been prepared similarly in the presence of ammonium iodide. Reduction with (ⁿBu₄N)OH provides (ⁿBu₄N)[M(pc^2–)₂] · x CH₃OH (M = Y ( 8 ), Sc ( 9 ); 0 9 x 9 1). Spectral properties (UV/VIS/NIR; IR; resonance Raman) of diphthalocyaninates in their different ring oxidation states (2–/2–; 2–/1–; 1–/1–) are discussed. 1 – 3 crystallise in the tetragonal (P4/ncc), 5 – 9 in the orthorhombic (Pna2₁), 10 , 11 in the triclinic (P‐1), and 4 , 12 – 14 in the monoclinic crystal system ( 4 : P2₁/m; 12 : C2/c; 13 , 14 : P2/c). Ecliptic rotamers with skew angles ranging from 4.1° to 6.0° are found in 1 – 3 , and staggered rotamers with skew angles ranging from 35.8° to 45.0° are found in 4 – 14 . The mean M–N_i bond lengths and interplanar distances increase monotonically with the ionic radius of the metal ion. Both distances deviate notably from this linear correlation in the Sb^III and Bi^III derivatives. The discrepancy is presumably due to the sterical dominance of the ns² lone‐pair character. The actual size of eight co‐ordinated Sb^III and Bi^III is estimated to be R₈ ≈ 1.02(Sb)/1.11(Bi) Å. In every complex salt, the pc ligand is severely distorted from planarity and can adopt domed, saddled, waved and mixed non‐planar conformations; the crystal symmetry is the most important factor for the conformational heterogeneity.     

Phytochemical components,total phenol and mineral contents and antioxidant activity of six major medicinal plants from Rayen,Iran

The aim of this work was to evaluate the phytochemical components, minerals, the antioxidant activity and total phenol contents of the essential oil from aerial parts of six major medicinal plants in Rayen, Iran. The plants included Ranunculus arvensis, Teucrium polium, Dracocephalum polychaetum, Kelussia odoratissima, Artemisia sieberi and Thymus kotschyanus. Total phenol content ranged from 0.03 to 0.158 mg/mL. A. sieberi showed the highest radical scavenging ability (IC₅₀ = 94 μg/mL). The amount of minerals ranged as follows: P (0.23–29%), K (1.08–4.76%), Ca (0.78–2.35%), Mg (0.24–0.94%), Cu (8.3–15 mg/kg), Cd (0.7–1.1 mg/kg), Pb (2–11.7 mg/kg) and Fe (250–1280 mg/kg). A total of 79 compounds were identified across all plants. The main components studied in the plants were l-perillaldehyde, biosol, carvacrol, 1,8-cineol, terpinyl acetate and 1,2,3,6,7,7 a-hexahydro-5 h-inden 5-one.     

Comparison of the RHF,NDDO, and MOM molecular one-electron expectation values calculated using minimum basis sets with Slater,Burns, Clementi,and BLMO exponents

The effect of different exponents, Slater, Burns, Clementi, and Best Limited Molecular Orbital (BLMO ) on the approximate one-electron property expectation values from minimum basis-set calculations is reported for Roothaan–Hartree–Fock (RHF ), neglect of diatomic differential overlap (NDDO ), and maximum overlap method (MOM ) calculations on FH, CO, and LiH.     

Electrothermal atomic absorption spectrometric determination of lithium,sodium, potassium and copper in uranium without preliminary chemical separation

Graphite furnace atomization is used for the direct determination of Li (0.25–4 ppm), Na (8–70 ppm), K (20–300 ppm) and Cu (0.5–25 ppm) in uranium dissolved in nitric acid, with relative standard deviations of 4–9%. Only iron seriously depresses the signals from the alkali metals.     

Levels of mercury,cadmium, lead and other selected elements in canned tuna fish commercialised in Jordan

During 2010, the concentrations of mercury and eight other trace elements in 90 canned tuna samples commercialised in Jordan were determined using mercury analyser (Hydra C®) and the inductively coupled plasma-optical emission spectrometer (ICP-OES). The mean concentrations and ranges for elements analysed in mg?kg ^{? 1} (wet base) were as follows: total Hg (0.21; 0.06–0.57), Cd (0.06;?<?0.01–0.63), Pb (0.09; <0.04–0.24), total As (0.74; 0.11–1.56), Ni (0.51; 0.03–2.85), V (0.04; <0.03–0.1), Al (0.26; 0.08–1.63), Ba (0.13; 0.05–0.42) and Ag was not detected in any of the analysed samples (<0.02?mg?kg^?1). The data obtained in the present study compared well with data obtained from similar studies carried out in different parts of the world. Few samples had the mercury and cadmium levels slightly exceeding the Codex Committee on Food Additives and Contaminants draft guidelines. However, the estimated weekly intakes of these metals showed that there was no health risk associated with the consumption of the analysed canned tuna samples.     

Synthesis,characterization, thermal and redox behavior,and biological activity of Ni(II), Cu(II), and Zn(II) complexes containing pyridoxine and imidazole moieties

Several mixed ligand complexes [M(II)(PN)(B)] [M(II) = Ni(II), Cu(II), and Zn(II)] derived from pyridoxine (PN) and imidazoles (B), namely imidazole (him), benzimidazole (bim), histamine (hist), and L-histidine (his), were synthesized. The complexes are characterized by elemental analysis, IR, UV-Vis ¹H NMR, and ESR spectroscopy. In [M(II)(PN)B], the monovalent anion of PN is bidentate to M(II) (–O, –OH), him, bim monodentate (–N), hist bidentate (–N, –N), and his tridentate (–O, –N, –N). Magnetic moment studies showed that the Ni(II) complexes and Cu(II)–PN–his have octahedral configuration while the other Cu(II) complexes have distorted tetrahedral geometry. The g _∥/A _∥ values calculated from the X-band ESR spectra of Cu(II) complexes in DMSO at 300 and 77 K supports the geometry. The thermal behavior (TG/DTA) of the synthesized complexes indicates the presence of lattice as well as coordinated water in the complexes. The in vitro biological activity of the mixed ligand complexes was tested against common bacteria, yeast, and fungi. The results in comparison with the control indicate that most of the complexes exhibit higher biological activities. The oxidative DNA cleavage studies of the mixed ligand complexes were performed using gel electrophoresis.     

Synthesis and Efficiency of an Epoxy-Urea Chelating Resin for Preconcentrating and Separating Trace Bi,In, Sn,Zr, V And Ti From Solution Samples

Abstract

A new epoxy-urea chelating resin was synthesized from epoxy resin and used for the preconcentration and separation of trace Bi(III), In(III), Sn(IV), Zr(IV), V(V) and Ti(IV) ions from solution samples. The analyzed ions can be enriched at pH 5 at a flow rate of 1–4 ml/min, and can be also desorbed with 10 mL of 2 M HCl +0.1g NH₄F solution from the resin column, with recoveries over 97%. The chelating resin reused 6 times can still adsorb quantitatively the Bi, In, Sn, Zr, V and Ti ions, and eighty to thousand-fold excesses of Ca(II), Mg(II), Cu(II), Zn(II), Al(III), Sb(III), Ni(II), Mn(II) and Fe(III) cause little interference with the enrichment and determination of these ions. The RSDs of the proposed method for the determination of 500–50 ng/ml Bi, In and Sn, 50–5.0 ng/ml Zr, V and Ti were in the range of 0.4 ～ 4.0%, the enrichment factor of the resin for the ions is in the range of 10–100. The recoveries of added standard in waste water are between 96% and 100%, and the concentration of each ion in alloy steel sample determined by the method is in good agreement with the reference value analyzed by a steel plant with average error <2.8%.     

Synthesis,spectroscopy and structure of cis,cis,trans:N,N;P,P;S,S-[bis(triphenylphosphine)] [bis(pyrimidine-2-thiolato)]ruthenium(II)

Reaction of RuCl₂(PPh₃)₃with pyrimidine-2-thione (HpymS) in a 1:2?mol ratio in dry benzene in the presence of triethylamine as base yielded a complex of stoichiometry [Ru(pymS)₂(PPh₃)₂] (1). This has been characterized using analytical data and IR, ¹H, ¹³C and ³¹P NMR spectroscopy. ¹H NMR confirmed the deprotonation of HpymS. ³¹P NMR spectra showed a single peak confirming equivalent P atoms. Complex 1 crystallizes in space group Pī and HpymS acts as a η²-N,S-deprotonated bidentate anionic ligand. The coordination geometry around the Ru center is distorted octahedral with cis dispositions of P atoms, as well as two N atoms of pymS^– and trans S atoms of pymS^–. Important bond distances and angles are: Ru–N, 2.119(2), 2.106(2); Ru–S, 2.4256(8), 2.4413(8); and Ru–P, 2.3266(7), 2.3167(7)?Å; P(2)–Ru(1)–P(1), 96.07(3); N(21)–Ru(1)–N(11), 83.46(9); and S(1)–Ru(1)–S(2), 153.02(3)°.     

Compatibility study of tobramycin and pharmaceutical excipients using differential scanning calorimetry,FTIR, DRX,and HPLC

Differential scanning calorimetry (DSC), isothermal stress testing–Fourier transform infrared spectroscopy (IST–FTIR), isothermal stress testing–high-performance liquid chromatography, and powder X-ray diffraction (PDRX) were used as screening techniques for assessing the compatibility of tobramycin with some currently employed ophthalmic excipients. In the first phase of the study, DSC was used as a tool to detect any interaction. The absolute value of the difference between the enthalpy of the pure tobramycin melting peak and that of its melting peak in the different analyzed mixtures was chosen as a parameter of the drug–excipient interaction degree. DSC results demonstrated that benzalkonium chloride, monobasic sodium phosphate, boric acid, edetate disodium, sodium metabisulfite, thimerosal, and potassium sorbate interact with tobramycin. Taking into account these results, it could be suggested that some of the changes observed in the IST–FTIR spectra of binary blends of tobramycin and some of the excipients would account for a possible interaction between the mixture component. In this study, PDRX did not provide much information, since only tobramycin–thimerosal interactions could be detected. DSC and IST–FTIR are suitable and simple methods for the detection of potential incompatibilities between active pharmaceutical ingredient (API) and excipients.

     

Coordination polymers of glutaraldehyde with glycine metal complexes: synthesis,spectral characterization,and their biological evaluation

Glycine metal complexes were prepared by the reaction of glycine with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) in 1?:?2 molar ratio. Thereafter their condensation polymerization was done with glutaraldehyde to obtain polymer metal complexes. All the synthesized polymer metal complexes were characterized by elemental analysis, FT-IR, ¹H-NMR, and UV-Vis spectrometry, magnetic susceptibility, and thermogravimetric studies. The analytical data of all the polymers agreed with 1?:?1 molar ratio of metal complex to glutaraldehyde and magnetic moment data suggest that PGG–Mn(II), PGG–Co(II), PGG–Ni(II), and PGG–Cu(II) have an octahedral geometry around the metal atom, whereas the tetrahedral geometry was proposed for PGG–Zn(II) polymer. The PGG–Mn(II) and PGG–Cu(II) showed octahedral geometry. Thermal behavior of the polymer metal complexes was obtained at a heating rate of 10°C?min^?1 under nitrogen atmosphere from 0°C to 800°C. The antimicrobial activities of synthesized polymers were investigated against Streptococcus aureus, Escherichia coli, Bacillus sphaericus, Salmonella sp. (Bacteria), Fusarium oryzae, Candida albicans, and Aspergillus niger (Yeast).     

Conformational behavior on 2,2,3-trisubstituted 1,2,3,4-tetrahydroquinoline alkaloids,virantmycin, benzastatins,and their congeners,evaluated by semi-empirical molecular orbital calculations

The conformational behaviors on ring inversion between two half-chair conformers a and b in physiologically active 2,2,3-trisubstituted 1,2,3,4-tetrahydroquinoline alkaloids, virantmycin ( 1 ), benzastatin C ( 6 ), benzastatin D ( 7 ), and their congeners 2–5 , which were revealed by their nmr studies have been quantitatively evaluated by semi-empirical molecular orbital calculations (PM3). The geometries of respective half-chair conformers a and b in compounds 1–7 were optimized and it was found that their thermodynamic distributions are approximately valid in comparison with the coupling constants observed in their nmr experiments. Furthermore, these calculations estimated the energy barriers for ring inversion in compounds 1–7 in the range of ca. 4.86–11.13 kcal/mol, which were compatible with rapid interconversions between a and b at room temperature.     

Separation,optimization, and quantification of cytokinins by a recently developed amide-embedded stationary phase

In this study, some plant growth regulators known as cytokinins [kinetin (K), zeatin (Z), thidiazuron (TDZ), benzylaminopurine (BAP), and dimethylallylaminopurine (AAP)] were separated by HPLC using an amide-embedded mixed-mode stationary phase which was synthesized by Aral et al. in recent years. The effect of mobile phase content, mobile phase pH, buffer concentration, and temperature on separation process was studied. In addition, a quantitative determination of cytokinins from Salvia limbata extract was studied, and some validation parameters such as limit of detection (LOD), limit of quantification (LOQ), and relative standard deviation (RSD) were calculated as a range of 0.03–0.1, 0.1–0.26?mg/L, and 0.03–0.08, respectively.     

Preparation,characterization, and bioavailability of a phosphorylated human‐like collagen calcium complex

The aim of this study was to determine whether a phosphorylated human‐like collagen calcium (PHLC–Ca) complex showed a higher bioavailability than other calcium supplements. To improve the calcium‐binding ability of human‐like collagen (HLC), modified HLC was prepared by introducing a reactive phosphate group using a dry‐heating method, followed by the formation of PHLC–Ca in MOPS buffer. PHLC–Ca was characterized using atomic absorption spectrophotometry, Fourier transform infrared (FTIR), fluorescence quenching, circular dichroism (CD), and ultraviolet–visible absorption (UV–vis) spectroscopy. The calcium uptake test showed that the bioavailability of PHLC–Ca was higher than that of CaCl₂ and G‐Ca. Data from a mouse model of osteoporosis suggested that PHLC–Ca is superior for treating osteoporosis than CaCl₂ or G‐Ca. These results indicate that PHLC–Ca is a desirable calcium supplement for use in daily life and clinical application. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous determination of germanium,arsenic, tin and antimony by molecular emission cavity analysis after hydride generation and gas chromatographic separation

Arsenic (0.1–5 μg), antimony (1–40 μg), tin (0.5–10 μg) and germanium (0.2–10 μg) are determined simultaneously by reduction to their hydrides with sodium tetrahydroborate(III), followed by gas chromatographic separation on a column of 10% E-301 silicone gum rubber on Porapak Q, and measurement of the emissions at 490 nm in an oxygen/hydrogen flame within a cavity. Detection limits for 1-ml samples are 35 ng As, 400 ng Sb, 85 ng Sn and 100 ng Ge. A more sensitive determination of arsenic (0.05–3 μg) and antimony (0.1–5 μg) in binary mixtures is also described; the detection limits are 15 ng As and 40 ng Sb.     

Ethyl Chloroformate as a Derivatizing Reagent for Capillary GC Determination of Dopamine, Adrenaline, Putrescine, and Histamine

Putrescine (Pu), histamine (HA), phenylhydrazine (PHZ), octopamine (OA), dopamine (DA), adrenaline (AD), and noradrenaline (NA) as the ethyl chloroformate (ECF) derivatives have been analyzed by capillary gas chromatography. The derivatives were separated on a 30 m × 0.32 mm i.d. HP-5 column by temperature programming from 100 °C (held for 1 min) to 250 °C at 10 min^?1. The total run time was 16 min. Nitrogen was used as carrier gas at a flow rate of 4 mL min^?1 and detection was by FID. PHZ was used as internal standard. The split ratio was 10:1 (v/v). The calibration curves were linear in the range 4–60 ng injected (1 μL injection) with detection limits 1.3–4.0 ng per injection (1 μL). When the method was used for determination of DA and AD in pharmaceutical preparations the relative standard deviation (RSD) was in the range 1–2.5%. When the effect of several additives was tested these did not affect the analyses. Pu and HA were estimated in fish samples with RSD 0.9–1.1 and 0.9–1.2%, respectively.