Annali di chimica最新文献

Linen is the most historical Egyptian textile fibre liable to fungal deterioration. Fungal deterioration of dyed linen textiles may appear as undesirable different stains. In order to success in removing of fungal stains from biodeteriorated historical Egyptian dyed linen textiles, it is necessary to understand the nature and causes of these stains, hence their subsequent removal. So this paper aims to investigate the effect of fungi on dyed linen textiles. In this study linen textile samples were experimentally dyed by two different dyes, blue one as an example to vat dye and yellow one as an example to direct dye. This work is done on two of the most important dyes (Turmeric and indigo), which were popular in most of historical periods in Egypt. Dyed linen samples were experimentally biodegraded by thirty different fungal strains isolated previously from historical Egyptian linen samples. The produced change in colours of the biodeteriorated samples was detected visually. Also, the change in reflection spectra and colour differences produced to dyed linen textiles after fungal deterioration, were assessed and evaluated by using spectrophotometer. This study reported that most of tested fungi contribute to discoloration of all tested dyed linen samples. These results indicate that most of stains on historical Egyptian dyed linen textiles, may be fungal stains. The results confirm that undyed linen textiles more liable to fungal biodeterioration than dyed ones. Also the results show that yellow dyed linen textiles are more susceptible to fungal deterioration than blue dyed linen textiles. The obtained results show that Alternaria tenuissima, Chaetomium globosum, Chaetomium sp., Penicillium raistrickii, P. soppi, P. asperum, P. citrinum, Aspergillus carbonarius, A. fischeri, A. nidulans, A. terreus and A. niger, had showed the maximum colour changes of the deteriorated yellow dyed linen samples. The results also show that Alternaria tenuissima, Chaetomium sp., Penicillium asperum, P. citrinum, Aspergillus nidulans and A. spinulosus, had shown the maximum colour changes of the deteriorated blue dyed linen samples.

The present work reports analytical results relevant to voltammetric determination of Pt(II), Pd(II), Rh(III) [Platinum Group Metals (PGMs)] and Pb(II) in superficial water sampled in sites differently influenced by vehicle traffic, especially considering their temporal behaviour. For all the elements, in addition to detection limits, precision, expressed as relative standard deviation (s_r %) and accuracy, expressed as percentage recovery (R %) are also reported. In all cases they show to be good, being the former lower than 6 % and the latter in the range 94-105 %. A critical comparison with spectroscopic measurements is also discussed.

A sensitive and simple method for the simultaneous preconcentration of nutritionally important minerals in real samples has been reported. The method is based on the adsorption of Cu²⁺, Ni²⁺, Co²⁺ and Pb²⁺ on 4-propyl-2-thiouracil (PUT) loaded on activated carbon. The metals on the complexes are eluted using 5 mL 3 M HNO₃ in acetone. The influences of the analytical parameters including pH and sample volume were investigated. The effects of matrix ions on the retentions of the analytes were also examined. The recoveries of analytes were generally higher than 95 %. The detection limits for Cu²⁺, Ni²⁺, Co²⁺ and Pb²⁺ were 1.6, 1.3, 1.2, 2.3 ng ml^-1, respectively. The method has been successfully applied for these metals content evaluation in some real samples including natural water samples.

A new electrode was modified by multilayer films composed of heteropolyanion (SiW₁₂) and cationic polymer poly(diallyldimethylammonium chloride) through electrochemical growth. The modified electrode electrochemical behavior, the effect of solution pH and electrocatalytic response to the reduction of BrO₃^- and NO₂^- have been investigated. The result shows that the electrochemical process of multilayer films modified electrode including SiW₁₂ is a reversible process by electrochemical step. One-electron process has no proton participation in the first step, and one-electron process is accompanied by one proton participation in the second step and two-electron process is accompanied by two protons participation in the third step. The films grow uniformly, and the peak currents increase with increasing layer numbers. The peak currents increase with scan rate, and the reduced potentials of multilayer films shift negatively with increasing pH. The electrochemical mechanism of multilayer films was suggested.

The results of an experimental analysis carried out to investigate PM_2.5 concentration levels and the content of polycyclic aromatic hydrocarbons, as well as inorganic trace elements in the atmospheric particles are presented. Measurements were taken with a micrometeorological station equipped with an optical PM_2.5 detector, and simultaneously, particles were collected on filters for subsequent chemical analyses. The average value of daily PM_2.5 concentration is 21.5 ug/m3 and real-time measurements indicate that the average concentration during the day (8 am to 8 pm) is about 25 % lower than the nocturnal average. Short-time averages of PM_2.5 decrease when the wind speed increases as consequence of the more efficient mixing. Meteorological measurements indicate the presence of a local daily (breeze) circulation with wind blowing from the Alps or the Adriatic Sea and, during this circulation, larger concentrations were observed, with wind coming from the Alps. Days of high PM_2.5 concentration with dominant anthropic or with prevalent crustal contributions were identified.

Regarding trace metals, their average concentrations are comparable to those found in others urban areas, except for Cd (3 ng m^-3), probably due to the presence of glass-works in Murano. The highest concentrations are observed for K (99 ng m^-3) and Na (73 ng m^-3), which are the main constituents of marine spray, while the lowest concentrations are observed for elements such as Cs and Co (respectively 0.01 and 0.02 ng m^-3). Also the concentrations of PAH are comparable with those of other industrial areas, as their sum ranges from 0.16 ng m^-3 to 3.73 ng m^-3, but if considered as B(a)P toxicity equivalent, they are largely lower (0.036±0.026 ng m^-3). From the analyses of discriminating ratios, it has been found that the main origin of PAH in PM_2.5 samples may be petrogenic, probably related to the presence of refinery and petrochemical plants on the mainland, although the contribution of combustion processes cannot be excluded.

Aminylferrocene(FcAI)-Nanogold(NG) modified glassy carbon electrode (FcAI/NG/GCE) was prepared by the Au-N bond between Au and FcAI. Electrochemical impedance spectroscopy (EIS) was employed to study the surface of the modified electrode. The electrochemical behavior of dopamine (DA) on the modified electrode was investigated and it was found that the modified electrode had an obvious electrocatalytic effect on DA. Compared with a bare GCE, the modified electrode exhibited an apparent shift of the oxidation peak potential in the negative potential direction and a marked enhancement in the current response for DA. We investigated the determination of DA on the modified electrode by differential pulse voltammetry (DPV). Linear calibration curve was obtained in the range of 7.0×10^-7 mol/L to 6×10^-4 mol/L of DA in 0.1mol/L phosphate buffer solution (pH= 7.0) with a correlation coefficient of 0.9989. The detection limit (S/N=3) of DA was estimated to be 1.0×10^-7 mol/L. Especially, by using the modified electrode, we can separate the oxidation peaks of ascorbic acid (AA) and DA in the PBS and it was satisfactory for the determination of DA with the interference of AA.

The extraction of copper(II), nickel(II) and cobalt(II) from the aqueous phase with N,N'-bis(salicylaldehydene)-1,4-bis-(m-aminophenoxy)butane (MAS), which was synthesized from 1,4-bis(m-aminophenoxy)butane and salicylaldehyde, was studied. Microanalytical data, elemental analysis, UV-visible ¹H and ¹³C n.m.r. spectra and IR-spectra were used to confirm the structures. The extractability and selectivity of divalent cations were evaluated as a function of relationship between distribution ratio of the metal and pH or ligand concentration. Cu⁺² showed the highest extractability and selectivity at pH 6.0, whereas Ni⁺² and Co⁺² showed at pH 9.2. The stoichiometries of the compounds formed were estimated to be CuL, CoL, NiL, where L is N,N'-bis(salicylaldehydene)-1,4-bis-(m-aminophenoxy)butane. It was concluded that MAS can effectively be used in solvent extraction of copper(II), nickel(II) and cobalt(II) from the aqeous phase to the organic phase.

The development of a network to monitor surface waters is a critical element in the assessment, restoration and protection of water quality. In this study, concentrations of 42 pesticides – determined by GC-MS on samples from 11 points along the Ferrara area rivers – have been analyzed by chemometric tools. The data were collected over a three-year period (2002-2004). Principal component analysis of the detected pesticides was carried out in order to define the best spatial locations for the sampling points. The results obtained have been interpreted in view of agricultural land use. Time series data regarding pesticide contents in surface waters has been analyzed using the Autocorrelation function. This chemometric tool allows for seasonal trends and makes it possible to optimize sampling frequency in order to detect the effective maximum pesticide content.

For the first time, a novel, simple and reliable method for analysis of pymetrozine residues in flue-cured tobacco leaves has been developed utilizing HPLC-UV with liquid-liquid partition cleanup. Pre-treatment with ultrasonic extraction and liquid-liquid partition procedures gave preferable baseline separation and clean chromatograms by removing water-soluble and fat-soluble components which interfere with pymetrozine in the test. The performance of the method was evaluated and validated: the detection limit (LOD) was 0.005μg.mL^-1, the relative standard deviation (RSD) was 1.2 % (n=5), and the overall recovery was above 90 % at fortification levels of 0.200, 0.500, 1.000, and 5.000 mg.kg^-1. The proposed method was successfully employed for the determination of pymetrozine residues in twelve flue-cured tobacco samples collected from different regions of China.