Treatment of the solution extracted from metal contaminated soils by reverse osmosis and chemical precipitation

In this study a process for the remediation of soils contaminated by lead or copper is proposed, consisting of the operations in sequence: soil flushing, membrane treatment, acidification, and metal precipitation. Pb(II) and Cu(II) extraction from a synthetically contaminated soil using a 0.05 M EDTA aqueous solution were investigated in column. The metal removal efficiencies and the final soil metal concentration were 98.2% and 37.96 mg/g respectively for lead and 95.4% and 59.20 mg/kg for copper. The extracted solutions were concentrated through a membrane treatment to reduce the water content up to the 75% and to obtain a permeate metal concentration in compliance with the Italian Environmental Regulation. The recovery of the used EDTA from the retentate solution, with recovery yield of at least 85.4%, was also obtained through acidification. Metal precipitation from the filtered solution was then performed according two different methods, achieving metal removal yield of more than 99.4%.     

Absolute and/or relative detection limits in laser-based analysis: the end justifies the means

The absolute limit of detection usually expresses the minimum amount of analyte detectable, while the relative limit of detection refers to the minimum concentration of analyte detectable. These concepts and their differences are obviously familiar to all analytical spectroscopists. Nevertheless, the two definitions are used liberally in the literature. For example, it is not uncommon to refer to exceptional sub-femtograms detection limits for a technique used to analyse ultratrace levels of an element in water and to a modest part per million detection limit of another technique used to characterise the microdistribution of an element in a sample mass of about one microgram. In this paper, an attempt is made to point out that the terms ultratrace analysis and microanalysis must refer to two conceptually different approaches and that there are cases in which one definition is more appropriate than the other. It is argued that, while there is no objection in reporting both detection limits when a single technique is evaluated, one has to be careful in choosing the most appropriate definition when different analytical techniques are compared.     

High-throughput microwave-digestion procedures to monitor neurotoxic elements in body fluids by means of inductively coupled plasma mass spectrometry

Microwave (MW) digestion procedures with high sample throughput (simultaneous digestion of 36 or 80 samples) and procedural simplicity (disposable plastic tubes, or re-usable liners with screw-cap) were investigated for their efficiency in routine analyses of biological samples. Different digestion vessel materials were tested for metal leaching/adsorption and thermal resistance: quartz, glass, polyethylene (PE) and polystyrene (PS). For the instrumental quantification of Al, Bi, Cd, Co, Cr, Hg, Mn, Mo, Ni, Pb, Sb, and Tl at ultra-trace levels in urine, serum, and whole blood, sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) was used. The different pretreatment conditions and vessels were evaluated in terms of contamination risk, effective power of detection, accuracy, and precision. Results of analyses of serum, urine and whole blood certified reference materials (CRMs) were fully satisfactory for almost all the analytes. In the case of Hg, Mo, and Tl in serum digested in plastic containers the results were just below the lower limit of uncertainty of the certified range. On the basis of the present data the following MW procedures can be suggested: 1. for urine, digestion with nitric acid at atmospheric pressure in plastic vials; 2. for serum, digestion with nitric acid at atmospheric pressure in glass vessels; and 3. for whole blood, digestion under pressure in quartz tubes.Because of the levels of the procedural blanks, Bi was not measurable at the concentrations expected in human fluids, and Al was accurately detectable in whole blood only.     

Development of a new assay for the screening of hypochlorous acid scavengers based on reversed-phase high-performance liquid chromatography

A new assay for the screening of hypochlorite/hypochlorous acid (XOCl) scavengers, based on the reversed-phase high performance liquid chromatographic analysis of human serum albumin (HSA, 0.2% in 100 mM sodium phosphate, pH 7), before and after oxidation by XOCl (1.6 mM), was developed. XOCl induced a significant decrease of the area under the chromatographic peak of HSA at 280 nm due to the oxidation of the aromatic amino acids tryptophan and tyrosine, as suggested by the literature and by the chromatographic analyses and the electrochemical study performed here. The assay was validated by testing known XOCl scavengers such as ascorbic acid, cysteine, glutathione, S-methylglutathione and alpha-lipoic acid and other antioxidants such as carnosine and chlorogenic acid, which inhibited the oxidation of HSA. Quantitative activities were calculated using an original formula based on the changes of the area of the albumin peak. Electrochemical data collected here in a homogeneous medium showed that the anodic potentials of the antioxidants tested are less positive (ascorbic acid, chlorogenic acid and cysteine) or similar (alpha-lipoic acid) compared with those of the aromatic residues (tryptophan and tyrosine) of HSA oxidized by XOCl. However, as expected, carnosine, glutathione and S-methylglutathione were inactive at a glassy-carbon, gold or platinum electrode.     

The microwave-coupled hollow cathode — a novel radiation source in emission spectroscopy

The development of new excitation sources accounts for the renaissance during the 1970s of emission spectroscopy as a powerful analytical tool. Among these, the hollow cathode discharge is still expanding the scope of its applications.     

Activation energy barriers in the molecular relaxation dynamics of Li+ interacting with acyclic and cyclic polyethers in acetonitrile

Ultrasonic relaxation spectra of LiClO₄ plus the open chain polyether triglyme (TG) at C_LiClO4 ? 0.8 M, molar ratio R = [TG]/[LiClO₄] = 1, and at temperatures of 15, 25, 35, and 45°C in dry acetonitrile are reported. Corresponding spectra for LiClO₄ plus the macrocycle 12-crown-4 (12C4) at R = [12C4]/[LiClO₄] = 1, at 10, 15, 20, 25, 30, and 40°C, and C_LiClO4 = 0.32 M in acetonitrile are also reported. Both relaxation envelopes, for the two systems, have been fitted by two Debye relaxation processes and interpreted by the Eigen-Winkler reaction scheme: where “PE” symbolizes the polyether, Li⁺ … PE is a solvent separated species and LiPE⁺ and (LiPE)⁺ are two complex species. The temperature dependence of the relaxation spectra permits the calculation of the activation parameters for the forward and reverse processes for the system LiClO₄ + TG and for one of the two processes for the LiClO₄ + 12C4 system. Comparisons between the two sets of data lead to the conclusion that the much slower second relaxation process, in the case of the macrocycle, is attributable to a combination of an enthalpic and an entropic effect on the energy barrier for the present systems.     

Absolute and/or relative detection limits in laser-based analysis: the end justifies the means

The absolute limit of detection usually expresses the minimum amount of analyte detectable, while the relative limit of detection refers to the minimum concentration of analyte detectable. These concepts and their differences are obviously familiar to all analytical spectroscopists. Nevertheless, the two definitions are used liberally in the literature. For example, it is not uncommon to refer to exceptional sub-femtograms detection limits for a technique used to analyse ultratrace levels of an element in water and to a modest part per million detection limit of another technique used to characterise the microdistribution of an element in a sample mass of about one microgram. In this paper, an attempt is made to point out that the terms "ultratrace analysis" and "microanalysis" must refer to two conceptually different approaches and that there are cases in which one definition is more appropriate than the other. It is argued that, while there is no objection in reporting both detection limits when a single technique is evaluated, one has to be careful in choosing the most appropriate definition when different analytical techniques are compared.     

Catalytic chain-breaking pyridinol antioxidants

When assayed for their capacity to inhibit azo-initiated peroxidation of linoleic acid in a water/chlorobenzene two-phase system, tellurium-containing 3-pyridinols were readily regenerable by N-acetylcysteine contained in the aqueous phase. The best inhibitors quenched peroxyl radicals more efficiently than alpha-tocopherol, and the duration of inhibition was limited only by the availability of the thiol reducing agent. The compounds were also found to catalyze reduction of hydrogen peroxide in the presence of thiol reducing agent.     

Portable X-ray fluorescence device reveals the artistic palette of Carlo Bononi,Baroque artist from Ferrara

The principal aim of the in situ X-ray fluorescence (XRF) analysis on the canvas “The Coronation of the Virgin” was to characterise the colour palette of Carlo Bononi (Ferrara, 1580–1632), a lesser-known artist of the early Baroque period in Ferrara. More than 100 points were collected by means of an XRF spectrometer, but the presence of many overlapping painted layers left some doubts about the preparation and the background layers. The scanning electron microscopy with energy dispersive spectrometer analysis on two samples resolved some of these doubts. The results obtained indicate the use of typical 17th century pigments, such as lead white, vermilion, azurite and a copper-based green. For yellow pigments, the artist used the yellow ochre in some cases, while in others he used lead-tin yellow. We also individuated at least three different shades of umber. Almost all the pigments have been identified and they are the first step in establishing the technical apparatus necessary to understand the modus operandi of the Ferrarese artist.