The formation constants of dioxouranium(VI) - 1,2,3-propanetricarboxylate [tricarballylate (3-), TCA] complexes were determined in NaCl aqueous solutions at 0 ≤ I / mol L -1 ≤ 1.0 and t = 25 °C, by potentiometry, ISE-[H + ] glass electrode. The speciation model obtained at each ionic strength includes the following species: ML-, MLH 0 , ML 2 4- and ML 2 H 3- (M = UO 2 2+ and L = TCA). The dependence on ionic strength of protonation constants of 1,2,3-propanetricarboxylate and of the metal-ligand complexes was modeled by the SIT (Specific ion Interaction Theory) approach and by the Pitzer equations. The formation constants at infinite dilution are [for the generic equilibrium p UO 2 2+ + q (L 3- ) + r H + = (UO 2 2+ ) p (L) q H r (2p−3q+r) ; β pqr ]: log β 110 = 6.222±0.030, log β 111 = 11.251±0.009, log β 121 = 7.75±0.02, log β 121 = 14.33±0.06. The sequestering ability of 1,2,3-propanetricarboxylate towards UOUO 2 2+ was quantified by using a sigmoid Boltzman type equation.
Four archaeological samples, unearthed from Qana in Yemen were analysed by analytical technique, currently applied in the field of petroleum geochemistry, and by gas chromatography coupled with a mass spectrometer (GC-MS). Sample no 1286 comes from a burned warehouse and samples no 964, 963 and 962 from the central sanctuary. These specimens were probably exposed to a heating source. In each case olibanum resin was identified according to the presence of their chemical markers corresponding to α-, β-boswellic and lupeolic acids (3α-hydroxy-olean-12-en-24-oic, 3α-hydroxy-urs-12-en-24-oic and 3α-hydroxy-lup-20(29)en-24-oic acids) and their respective O -acetyled derivatives (3α- O -acetyl -olean-12-en-24-oic, 3α- O -acetyl-urs-12-en-24-oic and 3- O -acetyl-lup-20(29)-en-24-oic acids). Concerning the thermal degradation state of samples, the GC-MS results are in agreement with the geochemical ones. Sample no 1286 and 964 correspond to ageing incense which has not undergone any heating action and are consequently relatively well preserved. Lastly, samples no 963 and 962 are thermally degraded resins and their gross composition data permits to conclude that sample no 963 is only partially burnt while sample no 962 has been much more degraded.
The construction and performance characteristic of a potentiometric PVC membrane sensor for the determination of triphenyltetrazolium chloride (TPTC1) is described. The sensor is based on the use of triphenyttetrazolium (TPT)tetraphenylborate (TPB) ion pair as ion exchange sites in PVC matrix in presence of dioctylphathalte as plasticizer. The TPT membrane sensor shows a stable, nearNernestian response for 6x 10(-6) -1 x 10(-2) M TPTC1 at 25 degrees C over the pH range 3-10 with cationic slope of 57.0 +/- 0.5. The lower detection limit is 4 X0(-6) M and the response time is 10-30 sec. Selectivity coefficients for TPTC1 relative to a number of different cations and anions were investigated, which there is negligible interferences. However, iodide, bromide and thiocyanate were interfering. The determination of 2.0- 3340.0 mu g/ml of TPTC1 in aqueous solutions shows an average recovery of 98.5 % and a mean relative standard deviation of 1.9 at 160 mu g/ml. The proposed method has been used for indirect potentiometric determination of ascorbic acid in its pharmaceutical formulations which are comparable favorably with those of British pharmacopoeia method. Precipitation titrations involving TPTC1 as tit-rant are monitored with NaTPB using the proposed membrane sensor; the inflection break is about 300 mV.
Annali di ChimicaVolume 97, Issue 11-12 Editorial Editorial: Annali di Chimica 11-12/2007 Francesco De Angelis, Francesco De AngelisSearch for more papers by this author Francesco De Angelis, Francesco De AngelisSearch for more papers by this author First published: 20 November 2007 https://doi.org/10.1002/adic.200790117AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume97, Issue11-12November 2007 RelatedInformation
Glassy carbon electrode (GCE) is covalently modified with aspartic acid (Asp). The modified electrode is used for the simultaneous electrochemical determination of hydroquinone (HQ) and catechol (CC) and shows an excellent electrocatalytical effect on the oxidation of HQ and CC by cyclic voltammetry (CV) in 0.1 mol/L acetate buffer solution (pH 4.5). In differential pulse voltammetric (DPV) measurements, the modified electrode could separate the oxidation peak potentials of HQ and CC present in binary mixtures by about 101 mV though the bare electrode gave a single broad response. A successful elimination of the fouling effect by the oxidized product of HQ on the response of CC has been achieved at the modified electrode. The determination limit of HQ in the presence of 0.1 mmol/L CC was 9.0 × 10 -7 mol/L and the determination limit of CC in the presence of 0.1 mmol/L HQ was 5.0 × 10 -7 mol/L. The proposed method has been applied to the simultaneous determination of HQ and CC in a water sample with simplicity and high selectivity.
The empirical parameters of a two-parameter SIT equation were determined for some 1:2 electrolytes: chlorides, bromides, iodides, nitrates, perchlorates of alkali earth metals and sulfates of alkali metals. A wide range of ionic strengths (0 < I < or = 18 mol kg(-1)) and t = 25 degrees C was considered. Canonical correlation analysis showed quite significant correlations between SIT and Pitzer interaction coefficients for different classes of 1:2 type electrolytes.
Fragments of wall paintings from Istria, coming from the Basilica of Guran near Vodnjan, from the cemeterial Church of Saint Simeon in Guran and from the Benedictine monastery of Santa Maria Alta near Bale were studied. The analytical instrumental techniques used were Optical Microscopy, Scanning Electron Microscopy equipped with an EDS microanalysis detector, X Ray diffraction, FTIR infrared Spectroscopy and Raman Spectroscopy. Red and yellow pigments used in Guran and Bale have bean derived from red and yellow istrian bauxites, as already demonstrated for works from 11(th) to 15(th) century. The blue pigment found in the paintings of the Bale Chapel is a lapislazzuli blue; this fact confirms the literature data referring to the period from 11(th) to the 16(th) century. The materials and pigments used at Bale and Guran fit with the Istrian tradition and history of painting going back to the first Carolingian period.
A new ultraviolet spectrophotometric method has been developed for the direct qualitative determination of captopril in pharmaceutical preparation and biological fluids such as human plasma and urine samples. The method was accomplished based on parallel factor analysis (PARAFAC) and partial least squares (PLS). The study was carried out in the pH range from 2.0 to 12.8 and with a concentration from 0.70 to 61.50 microg ml(-1) of captopril. Multivariate calibration models PLS at various pH and PARAFAC were elaborated from ultraviolet spectra deconvolution and captopril determination. The best models for this system were obtained with PARAFAC and PLS at pH = 2.04 (PLS-PH2). The applications of the method for the determination of real samples were evaluated by analysis of captopril in pharmaceutical preparations and biological (human plasma and urine) fluids with satisfactory results. The accuracy of the method, evaluated through the root mean square error of prediction (RMSEP), was 0.58 for captopril with PARAFAC and 0.67 for captopril with PLS-PH2 model. Acidity constant of captopril at 25 degrees C and ionic strength of 0.1 M have also been determined spectrophotometrically. The obtained pKa values of captopril are 3.90 +/- 0.05 and 10.03 +/- 0.08 for pKa. and pKa2, respectively.
A time-resolved fluoroimmunoassay (TR-FIA) was developed for the determination of hexoestrol (HES) residues in animal tissues. The limit of detection (LOD) was determined to be 0.02 ng g(-1) and the limit of quantification (LOQ) was less than 0.12 ng g(-1). The results obtained by the TR-FIA and ELISA showed a good correlation. The established TR-FIA was validated for the determination of market chicken muscle tissues and confirmed by high-performance liquid chromatography and tandem mass spectrometry (LC-MS-MS). This proposed technique could be applied to routine residue analysis.
A highly selective, sensitive and rapid method for the determination of trace amounts of inorganic mercury based on the reaction of Hg (II) with 6-mercaptopurine and the solid phase extraction of the complex on C18 membrane disks was developed. The 6-mercaptopurine selectively reacts with Hg (II) to form a complex in the pH range of 5-8. This complex was preconcentrated by solid phase extraction with C18 disks. An enrichment factor of 100 was achieved. The molar absorptivity of the complex is 0.26 x 10(-6) L. mol(-1) cm(-1) measured at 315 nm. The Beer's law is obeyed in the concentration range of 0.002-0.048 microg mL(-1). The relative standard deviation for eleven-replicated measurement of 0.04 microg mL(-1) is 1.5 %. The detection limit is 0.001 microg mL(-1) in the water samples. The advantage of the method is that the determination of Hg (II) is free from interference of almost all the cations and anions found in environment and wastewater samples. The determination of Hg (II) in water samples of different origins and marine sediment were carried out by the present method and cold vapor atomic absorption spectrometry (CVAAS). Also the method's accuracy was investigated by using SRM 2709. The obtained results by the present procedure were in good agreement with those of the CVAAS and certified value, so that the applicability of the proposed method was confirmed for the real samples.
A model was developed to predict the steady-state [*OH] in the surface layer of natural waters as a function of nitrate, inorganic carbon (IC) and dissolved organic matter (DOM). The parameter values were studied in the range detected in shallow high-mountain lakes, to which the model results are most relevant. Calculations indicate that [*OH] increases with increasing nitrate and decreasing IC, and conditions are also identified where [*OH] is directly proportional, inversely proportional or independent of DOM. Based on the model results it is possible to predict the half-life time, due to reaction with *OH, of given dissolved compounds, including organic pollutants, from the water composition data.
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 complexation of the Cu2+ ion with 2-Hydroxybenzamide (salicylamide, HL) has been studied, at 25 degrees C, by potentiometric measurements with a glass electrode in NaCIO4 media for ionic strength ranging from 0.5 to 3 mol/dm3. The data are consistent with the formation of the complexes CuH(-1)(HL)+, CuH(-2)(HL)2, Cu2H(-2)(HL)2(2+) and CuH(-2)(HL). The minor species, Cu2H(-2)(HL)2(2+) and CuH(-2)(HL), amount to at least 20% of the total copper. Elaboration of the data according to the Specific Interaction Theory yields the constants valid in the infinite dilution reference state: [formulas: see text] and the interaction coefficients (kg/mol) of complex species with medium ions: b(L-,Na+) = 0.11 +/- 0.03; b(CuH(-1)(HL)+,NaClO4) = 0.17 +/- 0.05; b(CuH(-2)(HL)2,NaClO4) = 0.11 +/- 0.05; b(Cu2H(-2)(HL)2(2+),NaClO4) = 0.2(7) +/- 0.1; b(CuH(-2)(HL),NaClO4) = -0.0(3) +/- 0.1.
An Ion Chromatographic (IC) method for the determination of six organic acids and three inorganic anions in alkaline solutions was reported. Formic, acetic, propionic, oxalic, succinic, glutaric acid, F-, Cl-, and SO42- were separated and determined in 33 min. The analytes were removed from Bayer liquor by using an ion-exchange resin column. The chromatographic separation was achieved with only one IonPac AS11-HC column thermostated at 30 degrees C. Organic acids and inorganic anions were detected with a suppressed conductance detector. The precision results' showed that the repeatability and reproducibility were < 2.94 and < 1.37%, respectively. The accuracy of the method was assessed by the recoveries ranging from 86.3 to 105.6%. Under optimum conditions the detection limits ranged from 0,008 to 0.053 mg/l.
In the Vinica Fortress, Republic of Macedonia, 50 undamaged terra cotta icons and 100 fragments, all dated 6th-7th century, were found. In order to determine the provenance of these unique terra cotta icons, the mass fractions of 19 different chemical elements were previously determined in ten fragments of the terra cotta icons and thirty three samples of clays from eight different sites from the region. Due to the dimensionality and complexity of the experimental data, the archaeometric results were treated with self-organising maps (SOM). The results obtained using SOM were compared with the ones obtained using principal component analysis. Both chemometric methods revealed that Vinica terra cotta icons were made from clay from Grncarka, 2.5 km South-East from the Vinica Fortress.
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 PM2.5 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.
Annali di ChimicaVolume 97, Issue 3-4 p. 135-139 Short Communication Photodegradation of Xenobiotic Compounds Relevant to Estuarine Waters Serge Chiron, Serge Chiron Laboratoire Chimie et Environnement, Université de Provence, 3 place Victor Hugo, 13331 Marseille cedex 3, FranceSearch for more papers by this authorClaudio Minero, Claudio Minero Dipartimento di Chimica Analitica, Università di Torino, Via Pietro Giuria 5, 10125 Torino, Italy, http://www.environmentalchemistry.unito.itSearch for more papers by this authorDavide Vione, Corresponding Author Davide Vione davide.vione@unito.it Laboratoire Chimie et Environnement, Université de Provence, 3 place Victor Hugo, 13331 Marseille cedex 3, France http://www.abcrg.itDipartimento di Chimica Analitica, Università di Torino, Via Pietro Giuria 5, 10125 Torino, Italy, fax: (++39)-011-6707615Search for more papers by this author Serge Chiron, Serge Chiron Laboratoire Chimie et Environnement, Université de Provence, 3 place Victor Hugo, 13331 Marseille cedex 3, FranceSearch for more papers by this authorClaudio Minero, Claudio Minero Dipartimento di Chimica Analitica, Università di Torino, Via Pietro Giuria 5, 10125 Torino, Italy, http://www.environmentalchemistry.unito.itSearch for more papers by this authorDavide Vione, Corresponding Author Davide Vione davide.vione@unito.it Laboratoire Chimie et Environnement, Université de Provence, 3 place Victor Hugo, 13331 Marseille cedex 3, France http://www.abcrg.itDipartimento di Chimica Analitica, Università di Torino, Via Pietro Giuria 5, 10125 Torino, Italy, fax: (++39)-011-6707615Search for more papers by this author First published: 12 February 2007 https://doi.org/10.1002/adic.200790013Citations: 11 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume97, Issue3-4February 2007Pages 135-139 RelatedInformation
A highly sensitive solid phase microextraction – high performance liquid chromatographic method has been developed for the determination of copper(II) using morpholine-4-carbodithioate (MDTC) as an analytical reagent. The MDTC formed yellowish- brown species of copper(II) at a pH range of 2-9 and complex was sorbed onto PDMS fiber. The Cu(II)-MDTC complex shows maximum absorbance at 430 nm and can be separated on C18 column by using acetonitrile : water (80 : 20) at a flow rate of 1.0 ml min-1.The detection limit of method was found to be 0.51 μg L-1. The interference due to common metal ions were studied. The repeatability of the method was checked by finding the relative standard deviation. The developed method was successfully employed for the determination of copper(II) in different alloy samples and the results were compared with existing methods.
