Determination of Arsenic(III) and Total Arsenic at Trace Levels in Baby Food Samples via a New Functionalized Magnetic Graphane Oxide Nanocomposite.

Baby food safety is an essential issue in health policy. For this reason, a simple, cheap, and fast analytical procedure to developed arsenic(III) and total arsenic determination in baby food samples using functionalized magnetic graphane oxide nanocomposite. A new nanocomposite anchored of tiopronin (TSH) magnetic graphane oxide (GO-PG4@Fe3O4-TSH) was first synthesized/characterized and used as an adsorbent to determine arsenic(III) and total arsenic for baby food samples. Arsenic(III) was directly determined on GO-PG4@Fe3O4-TSH nanocomposite at pH 4.5. The determination of total arsenic used KI and L( +) ascorbic acid solution as reducing reagents. The parameters influential on arsenic(III) determination in the baby food samples including the sample's pH, adsorption time, amount of GO-PG4@Fe3O4-TSH, eluent type, sample volume, reducing reagent type and amount, and also foreign ion effect were investigated. The GO-PG4@Fe3O4-TSH carrying As(III) could easily be separated from baby food samples via applying an external magnetic field. The detection limit for arsenic(III) was found as 0.11 µg L-1, while the limit of quantification values was computed as 0.37 µg L-1. The precision of results, expressed as relative standard deviation, was always lower than 1.6% at 1 mg L-1 As(III) levels. The accuracy of this method was confirmed by analysis of certified reference material. The method was successively applied to determine arsenic(III) and total arsenic in baby food samples.

A new fluorescence reagent: Synthesis, characterization and application for speciation of arsenic (III)/(VI) species in tea samples.

A sensitive and selective fluorimetric method for the rapid determination of trace amounts of As(III)/As(V) species in certain tea samples forms the basis of the study. 3',6'-bis(diethylamino)-2-{[(1E)-(4,5-dimethyl-2-furyl)methylene]amino}spiro[isoindole-1,9'-xanthen]-3(2H)-one (DMBD), was synthesized and characterized as a new fluorescence reagent for the speciation of As(III)/As(V) species. As(III) was quantitatively recovered with fluorescence reagent at concentrations between 0.5 and 1.5 mol L-1 of HNO3, while As(V) was not quantitatively recovered at any pH. The optimum conditions for the speciation of As(III)/As(V) species were investigated on certain commonly tested experimental parameters such as acidity and pH of the sample, amount of reagent, effects of temperature, and interfering ions etc. In order to determine trace amounts of total arsenic, KI and l(+) ascorbic acid were used to reduce As(V) to the trivalent state in the sample solution prior to determination. The concentration of As(V) in the sample solution were calculated by the difference in concentration between As(III) and the total arsenic in the sample solution. The study yielded a linear function of the concentration of As(III) in the 0-5 mg L-1 range with a detection limit of 0.22 µg L-1. The relative standard deviation was found to be 0.3% for the 0.5 mg L-1 As(III) level. The proposed method was successfully applied for the determination of trace amounts of As(III) and As(V) in certain tea samples. The results of analysis of the certified reference material (INCT-TL-1 tea sample) was found to be in good agreement with the certified value.

Xanthine oxidase inhibitory activity of new pyrrole carboxamide derivatives: In vitro and in silico studies.

Pyrrole carboxamide rings are rarely used as active scaffold in designing inhibitors for enzymes. Herein, we described the structure-activity relationship for novel xanthine oxidase inhibitors based on the pyrrole carboxamide scaffold. A series of novel-substituted pyrrole carboxamide derivatives were synthesized and characterized; their in vitro and in silico inhibitory activities were determined against xanthine oxidase. Among these compounds, those which contain no substituent and one methyl group at the para-position of the phenyl moiety in the main structure, respectively, were found out as most active according to the xanthine oxidase inhibition activity study. In silico techniques reveal why these compounds display more activities than others, based on their binding interactions with xanthine oxidase and the surface scanning results of the enzyme. Furthermore, the binding energy calculations displayed good agreement with the experimental activity values.

A new turn-on fluorimetric method for the rapid speciation of Cr(III)/Cr(VI) species in tea samples with rhodamine-based fluorescent reagent.

A new fluorimetric method with rhodamine-based fluorescent agent was developed for the rapid speciation of Cr(III)/Cr(VI) in tea, soil and water samples. The system, which utilizes a fluorescent reagent, was used for the first time after synthesis/characterization of 3',6'-bis(diethylamino)-2-{[(1E)-(2,4-dimethoxyphenyl)methylene] amino}spiro[isoindole-1,9'-xanthen]-3(2H)-one (BDAS). The reagent responds instantaneously at room temperature in a 1:1 stoichiometric manner to the amount of Cr(III). The selectivity of this system for Cr(III) over other metal ions is remarkably high, and its sensitivity is below 0.01mgL-1 in aqueous solutions which enables a simplification without any pretreatment of the real sample. The method has a wide linear range of 0.1-10mgL-1 and a detection limit of 0.15µgL-1 for Cr(III) while the relative standard deviation was 0.1% for 0.1mgL-1 Cr(III) concentration. The results of detection and recovery experiments for Cr(III) in tea, soil and water were satisfactory, indicating that the method has better feasibility and application potential in the routine determination and speciation of Cr(III)/Cr(VI). The results of analysis of the certified reference material (INCT-TL-1 tea sample and CWW-TM-D waste water) are in good agreement with the certified value.

Synthesis, characterization and application of a new fluorescence reagent for the determination of aluminum in food samples.

A new sensitive fluorimetry method for the simple and rapid measurement of aluminum in some food samples, which used 3',6'-bis(diethylamino)-2-{[(1E)-(4-ethoxyphenyl) methylene] amino}spiro[isoindole-1,9'-xanthen]-3(2H)-one (DEMAX) for Al(III) chelation is described herein. The fluorescence intensity of the aluminum-DEMAX complex remains unaltered for over 24h at room temperature and is a linear function of the concentration of aluminum in the 0-1000mg/L range with a detection limit (LOD, defined as 3s/b) of 3.02µgL-1 and quantification limit (LOQ, defined as 10Sb/m) of 30µgL-1. The relative standard deviation (RSD) was 0.1% for a 1µgL-1 aluminum level. The influences of the analytical parameters such as pH, waiting time of aluminum-DEMAX complex, amount of reagent, effect of temperature etc. were investigated. The developed method was successfully used for assaying aluminum in some food samples and dialysis solution, measured by the new home-made fluorimetric system. The results of analysis of the certified reference material (INCT-TL-1) are in good agreement with the certified value.

A New Turn-On Fluorometric Detection Method for the Determination of Ag(I) in Some Food and Water Samples.

A new sensitive and selective turn-on fluorometry procedure for the determination of silver using a laboratory-built fluorometry system is described herein. After synthesis and characterization, a [2-((E)-{[3',6'-bis(ethylamino)-2',7'-dimethyl-3-oxospiro[isoindole-1,9'-xanthen]-2(3H)-yl]imino}methyl)cyclopenta-2,4-dien-1-yl] (cyclopenta-2,4-dien-1-yl)iron (DKMS) fluorescent reagent was used for the first time. Ag(I) was complexed with the new fluorescent reagent, and direct measurements were made using fluorometry without any separation/preconcentration. The fluorescence intensity of the Ag(I)-DKMS complex remained unchanged for over 18 h at room temperature and was a linear function of the concentration of Ag(I) in the 0-2.5 mg/L range. The optimum determination conditions were established by testing different reagent quantities, the acidity and pH of the sample, and the effect of temperature and interfering ions. The LOD of the method was 1.00 µg/L whereas the RSD was 0.1% for 0.1 mg/L Ag(I) concentration. "The developed method was applied successfully for the Ag(I) determination of silver in burn cream, anode slime, some food and water samples". Results of the analysis of Certified Reference Materials (NCS DC73349 Bush Branches and Leaves - Trace Elements, and CWW-TM-D Certified Wastewater and Trace Metals) are in good agreement with the certified values.

A New Chelating Reagent: Its Synthesis/Characterization and Application for the Determination of Cd(II) and Ni(II) in Various Food and Make-Up Product Samples by FAAS Using Simultaneous Microextraction Sampling.

A new and simple dispersive liquid-liquid simultaneous microextraction procedure was developed for the rapid separation and simultaneous extraction/preconcentration of Cd(II) and Ni(II) at ultratrace amounts. Microextraction of the analytes was carried out in the presence of 2-methyl-5-[(Z)-pyridin-4-yldiazenyl]quinolin-8-ol as the chelating reagent. Chloroform and ethanol were used as the extraction and dispersive solvents. Various parameters that influence the microextraction procedure's efficiency-such as pH, centrifugation rate and time, reagent concentration, and sampling volume on the recovery of analytes-were examined. The calibration curves were linear in the range of 0.01-1.25 and 0.075-5 mg/L with LODs of 0.25 and 0.84 µg/L, and with a preconcentration factor of 94, for Cd(II) and Ni(II), respectively. Precision was >1.0%. The accuracy of the method was confirmed by analyzing the Certified Standard Reference Material (CWW-TMD: Certified wastewater-Trace metals, wastewater). The results show that the dispersive liquid-liquid simultaneous microextraction pretreatment is a sensitive, rapid, simple, green, and safe method for the separation/preconcentration of cadmium and nickel.

A new chelating reagent and application for coprecipitation of some metals in food samples by FAAS.

A new, simple and rapid coprecipitation method has been developed to separate and preconcentrate traces of Co(II), Cu(II), Fe(III), Pb(II) and Mn(II) in different samples prior to their determinations by flame atomic absorption spectrometry (FAAS). 2-[(E)-(8-hydroxy-2-methylquinolin-5-yl) diazenyl] benzoic acid (QAN) was firstly synthesized and characterized as a new chelating reagent for determination of some metals. IR spectra, (1)H-NMR spectrum and elemental analysis were evaluated for the characterization of the reagent. These metals were quantitatively recovered with Ni(II)/QAN precipitate in pH range of 8-10. Different factors such as sample volume, amount of QAN, and Ni(II) as carrier element, sample volume, and matrix effects for improving the quality of the preconcentration procedure were optimized. Under optimized experimentally established conditions, analytical detection limits were in the range of 0.03-0.83µgL(-1), while precision (RSD) was <3.5%, and enrichment factor was obtained as 100. The accuracy of the presented coprecipitation method was verified by the analysis of certified reference materials. The method was applied to the determination of the analytes in real samples such as food samples and make up products, and accuracy was found high (recoveries >95%).

Development of a new on-line system for the sequential speciation and determination of chromium species in various samples using a combination of chelating and ion exchange resins.

A new on-line flow injection (FI) procedure for the sequential separation, preconcentration and speciation of Cr(III)/Cr(VI) species in different matrices is described based on the combining of solid phase extraction and flame atomic absorption spectrometry (FAAS). Poly 2-(5-methylisoxazol)methacrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid-co-divinyl-benzene and Dowex 21K resins were used as chelating and ion-exchange materials for the separation/preconcentration of Cr(III) and Cr(VI) ions, respectively. Trace amounts of chromium retained on the resins were eluted sequentially with HNO3 and then introduced directly to the nebulizer-burner system of FAAS. The optimum conditions such as pH of the sample solution, amount of the resin, volume of the sample and interfering ions, which are effective on the quantitative recovery of the analytes, were investigated for sequential determination of Cr(III) and Cr(VI) ions. The preconcentration factors were found to be 48 and 30 for Cr(III) and Cr(VI), and the detection limits corresponding to three times the standard deviation of the blank (3s/b) were 0.05 and 0.3 µg L(-1), respectively. The method was verified by analyzing a certified reference material. The proposed method was applied to the determination based on the speciation of chromium in various real samples with satisfactory results.

Synthesis, characterization and vibrational spectra analysis of ethyl (2Z)-2-(2-amino-4-oxo-1,3-oxazol-5(4H)-ylidene)-3-oxo-3-phenylpropanoate.

In the present study, the experimental and theoretical vibrational spectra of ethyl (2Z)-2-(2-amino-4-oxo-1,3-oxazol-5(4H)-ylidene)-3-oxo-3-phenylpropanoate (AOX) were investigated. The experimental FT-IR (400-4000 cm(-1)) and Laser-Raman spectra (100-4000 cm(-1)) of the molecule in the solid phase were recorded. Theoretical vibrational frequencies and geometric parameters (bond lengths, bond angles and torsion angles) were calculated using ab initio Hartree Fock (HF), Density Functional Theory (B3LYP and B3PW91) methods with 6-311++G(d,p) basis set by Gaussian 03 program, for the first time. The computed values of frequencies are scaled using a suitable scale factor to yield good coherence with the observed values. The assignments of the vibrational frequencies were performed by potential energy distribution (PED) analysis by using VEDA 4 program. The theoretical optimized geometric parameters and vibrational frequencies were compared with the corresponding experimental X-ray diffraction data, and they were seen to be in a good agreement with each other. The hydrogen bonding geometry of the molecule was also simulated to evaluate the effect of intermolecular hydrogen bonding on the vibrational frequencies. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies were found.

Novel acid mono azo dye compound: synthesis, characterization, vibrational, optical and theoretical investigations of 2-[(E)-(8-hydroxyquinolin-5-yl)-diazenyl]-4,5-dimethoxybenzoic acid.

Novel acid mono azo dye, 2-[(E)-(8-hydroxyquinolin-5yl)-diazenyl]-4,5-dimethoxybenzoic acid (HQD), was synthesized by coupling diazonium salt solution of 2-amino-4,5-dimethoxybenzoic acid (DMA) with 8-hydroxyquinoline (HQ). This dye was characterized by UV-vis, IR & Raman, (1)H and (13)C NMR spectroscopic techniques and elemental analysis. The normal coordinate analysis of HQD was also performed to assign each band in vibrational spectra. DFT (B3LYP and B3PW91) calculations were employed to optimize the geometry, to interpret NMR spectra, to calculate and to determine the stable tautomeric structure of the compound. Natural Bond Orbital (NBO) analysis was performed to investigate intramolecular interactions. The vibrational spectral data obtained from solid phase IR & Raman spectra were assigned based on the results of the theoretical calculations. UV-vis spectroscopic technique was employed to obtain the optical band gap of HQD. The analysis of the optical absorption data revealed the existence of direct and indirect transitions in the optical band gaps. The optical band gaps of HQD have been found 1.95 and 1.90eV for direct and indirect transitions, respectively.

Methyl (+/-)-1-ethyl-2-hydroxy-4-(4-methoxybenzoyl)-5-(4-methoxyphenyl)-3-oxo-2,3-dihydro-1H-pyrrole-2-acetate.

The title compound, C(24)H(25)NO(7), is a racemic mixture of 2,3-dihydro-1H-pyrrol-3-ones. It crystallizes in the triclinic system, space group P1, with Z = 2. The asymmetric unit contains two enantiomorphic molecules and the structure is stabilized by hydrogen-bond contacts.