Dynamic reaction cell ICP-MS for determination of total As, Cr, Se and V in complex matrices: still a challenge? A review

Mass interferences, caused by atomic or polyatomic species and having the same mass/charge ratio of the analyte, can be a severe limit for a reliable assay of trace and ultratrace elements by ICP-MS. The DRC? technology uses a reaction gas to overcome these interferences. Reactions of charge exchange, atom transfer, adduct formation, condensation and analyte association/condensation are the main mechanisms. Interfering ions tend to react with the gas exothermally, while, the analyte reacts endothermally. Selecting the most appropriate reaction gas in DRC-ICP-MS is the very critical point for the determination of strongly interfered elements. A careful evaluation of the reaction mechanisms and the chemistry involved are required. The DRC allows the use of different gases, among them, ammonia (NH(3)), methane (CH(4)), hydrogen (H(2)) and oxygen (O(2)) are the most known, but there are other potentially useful gases like nitrous oxide (N(2)O), nitrogen oxide (NO), carbon dioxide (CO(2)), fluoromethane (CH(3)F), sulphur hexafluoride (SF(6)) and carbon disulfide (CS(2)). This paper provides a review on the analytical challenges for a reliable assay of As, Cr, Se and V by DRC-ICP-MS and illustrates different approaches and mechanisms involved in the analysis of polymers, biological fluids (serum, urine and whole blood), rock, soil and particulate matter.     

Application of WDXRF in the provenance studies of Persian haft rang tiles: a statistical approach

An outstanding style of Persian tilework, which emerged from the north‐eastern Iran in the 15th century, was extensively used for decorating architectural facades during the Safavid period (from the 16th through the 18th century). This type of tilework, the so‐called haft rang, technically comprises of forming a clay body and firing two glazed layers on top of the body. In the present paper, the first analytical data concerning haft rang tiles is provided. To do so, forty three samples of Safavid haft rang bodies were analysed by wavelength dispersive x‐ray fluorescence (WDXRF) and the obtained data were handled by principal component analysis (PCA). The results showed that the 17th century haft rang tiles wherever found are local products; that is, Safavid tile‐makers have used local clay sources to make the bodies of haft rang tiles. The analytical data also showed that old tileworks, in general sense, can be simply replaced by newly manufactured tiles or, at least, all tilework revetments in an individual edifice might not have been produced in an identical workshop. Moreover, WDXRF was used as an accurate and precise method to determine the chemical composition and to support compositional classification in provenance studies and can be considered as a reliable alternative for studying the provenance of archaeological ceramics. Copyright © 2013 John Wiley & Sons, Ltd.     

The role of oxygen in the reduction of tetrazolium salts with nadh mediated by 5-methyl phenazonium methyl sulfate. An EPR and voltammetric study

The reduction of tetrazolium salts (namely INT, MTT and BNT) with NADH in the presence of catalytic amounts of PMS (5-methylphenazonium methylsulfate) was studied, and the influence of oxygen on the system was considered. The redox potentials of all the investigated compounds, the kinetic measurements, as well as the application of the Marcus theory confirmed that PMS and tetrazolium ions are reduced by NADH through an inner-sphere mechanism. The EPR investigations led to the detection of all possible radical species coming from PMS and tetrazolium ions and are in agreement with a mechanism which excludes any role of oxygen in the system NADH/PMS/tetrazolium for the formation of formazan.     

Flame atomic absorption and ICP-atomic emission spectroscopic determination of Cu, Zn and Cd in solid suspensions of biological samples

Summary A method, based on slurrying of solids, is described for the direct, routine flame atomic absorption (flame AAS) and inductively-coupled plasma atomic emission (ICP-AES) spectroscopic trace determination of Cu, Zn and Cd in solid biological samples. The sample powder (particles < 20 m) — between 40 and 100 mg — is firstly wetted with a 0.5% sodium hexametaphosphate solution and is then dispersed in a 5.6% v/v nitric acid solution. Both magnetic and ultrasonic stirring were evaluated. The latter proved to be the more effective especially when dealing with the higher concentration suspensions. The suspension is then aspirated directly into the spectrometer. Direct comparison with aqueous calibration standards can be used in all cases.All samples were analyzed with an accuracy of ±10% and a precision (relative standard deviation) of better than 7%. The limits of detection were as low as 2.0×10^–2 g/g for zinc. Sensitivities, reported as concentration required to give a 0.0044 absorbance signal, were as low as 2.4×10^–2 g/g for zinc. The advantages of this method are its simplicity, low cost, speed of analysis and simple and rapid calibration.

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Bestimmung von Cu, Zn und Cd in festen Suspensionen biologischer Proben durch Flammen-AAS und ICP-AES

Zusammenfassung Zur Spurenbestimmung von Cu, Zn und Cd in biologischen Proben durch Flammen-AAS und ICPAES wird eine Aufschlämmung von Festteilchen benutzt. Die pulverisierte Probe (mit Teilchengrössen < 20 um, 40–100 mg) wird zunächst mit 0,5%iger Natriumhexametaphosphatlösung benetzt und dann in 5,6%iger Salpetersäurelösung dispergiert. Besonderes bei höheren Konzentrationen hat sich Ultraschall-Rühren besser bewährt als magnetische Methoden. Die Suspension wird direkt in das Gerät eingeführt. In allen Fällen wurde der Vergleich mit wässrigen Standardlösungen durchgeführt. Die Richtigkeit betrug 10%, die Präzision (relative Standardabweichung) war besser als 7%. Die Nachweisgrenze lag für Zink bei 2×10^–2 g/g, die Empfindlichkeit (Extinktion 0,0044) bei 1,8×10^–2 g/g. Die Vorteile des Verfahrens sind: Einfachheit, niedrige Kosten, Schnelligkeit und einfache sowie rasche Eichung.

     

Development of an analytical method for monitoring worker populations exposed to platinum-group elements

The increasing industrial use of platinum-group elements (PGEs), namely Ir, Pd, Pt and Rh, and related allergies such as rhinitis, conjunctivitis, asthma, urticaria and contact dermatitis, have led to a growing need to monitor selected populations of exposed workers. In this study, the levels of PGEs were measured in indoor airborne particulate matter and in biological samples taken from employees of a plant where car catalytic converters are produced and precious metals are recovered from spent carbon catalysts. The development of an analytical procedure based on quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) for the analysis of PGEs in airborne particulate matter and on sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) for the analysis of PGEs in blood, serum, urine and hair is described. For airborne particulate matter deposited on filters, the limits of detection (LoDs) were found to be 0.006 ng m⁻³, 0.020 ng m⁻³, 0.018 ng m⁻³ and 0.006 ng m⁻³ for Ir, Pd, Pt and Rh, respectively. Repeatability of measurements ranged from 1.8 to 8.5%, while recovery was in the range from 92 to 102%. For biological samples LoDs in blood, serum, urine and hair ranged from (in ng l⁻¹) 0.2–0.6 for Ir, 5–10 for Pd, 1–3 for Pt and 2–3 for Rh. For all biological materials, the repeatability varied from 1.1 to 12% for the four elements. Recovery data for the determination of PGEs in biological matrices were found to range from 84.0 to 107.8%. The method was applied to the determination of either total or respirable airborne PGEs collected from five different work areas in the plant. The difference between areas with high and low exposure correlates closely with metal levels in hair, blood and urine. The correlation coefficients between Pt in airborne particulate matter and Pt in biological materials was 0.994, 0.991 and 0.970 for blood, hair and urine, respectively.     

Phosphine-substituted ruthenium carbonyl carboxylates

The behaviour of the [Ru₂(CO)₄(CH₃COO)₂]_n/tributylphosphine/acetic acid system has been investigated as a function of reaction conditions and molar ratios of reactants. Tricyclohexylphosphine and triethylphosphite were also used as ligands and investigation was extended to the related oxalic, malonic, succinic, glutaric and adipic acid derivatives. These derivatives were isolated and characterized in view of their possible role as catalysts in the homogeneous hydrogenation of carboxylic acids in the presence of phosphine- or phosphite-substituted ruthenium carbonyl derivatives.     

Use of a standard system to evaluate the matrix effect on the treatment of a solution from atrazine contaminated soils

The influence of humic substances on the electrochemical treatment of solutions resulting from the remediation of atrazine contaminated soil has been investigated. In particular the effect on the hydrogen peroxide production stage and the effect on the hydroxyl radical oxidation treatment have been separately studied. In order to quickly assess the possible inhibition of the removal, an inorganic system has been adopted as a standard system. The results confirm the validity of electrochemical technologies also for the treatment of a real effluent where a matrix effect is expected since the organic matter content affects only the hydrogen peroxide production.