Determination of tributyltin in marine sediment: Comité Consultatif pour la Quantité de Matière (CCQM) pilot study P-18 international intercomparison

The capabilities of National Metrology Institutes (NMIs—those which are members of the Comité Consultatif pour la Quantité de Matière (CCQM)of the CIPM) and selected outside "expert" laboratories to quantitate (C₄H₉)₃Sn⁺ (TBT) in a prepared marine sediment were assessed. This exercise was sanctioned by the 7th CCQM meeting, April 4–6, 2001, as an activity of the Inorganic Analysis Working Group and was jointly piloted by the Institute for National Measurement Standards of the National Research Council of Canada (NRC) and the Laboratory of the Government Chemist (LGC), UK. A total of 11 laboratories submitted results (7 NMIs, and 4 external labs). Two external laboratories utilized a standard calibration approach based on a natural abundance TBT standard, whereas all NMIs relied upon isotope dilution mass spectrometry for quantitation. For this purpose, a species specific ¹¹⁷Sn-enriched TBT standard was supplied by the LGC. No sample preparation methodology was prescribed by the piloting laboratories and, by consequence, a variety of approaches was adopted by the participants, including mechanical shaking, sonication, accelerated solvent extraction, microwave assisted extraction and heating in combination with Grignard derivatization, ethylation and direct sampling. Detection techniques included ICP–MS (with GC and HPLC sample introduction), GC–MS, GC–AED and GC–FPD. Recovery of TBT from a control standard (NRCC CRM PACS-2 marine sediment) averaged 93.5±2.4% (n=14). Results for the pilot material averaged 0.680±0.015 µmol kg^–1 (n=14; 80.7±1.8 µg kg^–1) with a median value of 0.676 µmol kg^–1. Overall, performance was substantially better than state-of-the-art expectations and the satisfactory agreement amongst participants permitted scheduling of a follow-up Key comparison for TBT (K-28), a Pilot intercomparison for DBT (P-43), and certification of the test sediment for TBT content and its release as a new Certified Reference Material (HIPA-1) with a TBT content of 0.679±0.089 µmol kg^–1 (expanded uncertainty, k=2, as Sn) (80.5±10.6 µg kg^–1).Electronic Supplementary Material Supplementary material is available in the online version of this article at .     

An automated neutron activation procedure for screening PCB content of oil

An analytical procedure for rapidly screening large numbers of oils for polychlorinated biphenyl (PCB) content has been developed and is now in routine use. Pontential levels of PCBs are inferred from chlorine concentrations as determined using the automated neutron activation analysis (NAA) facility at the Los Alamos National Laboratory Omega West Reactor. The technique is designed to screen up to 200 oil samples per eight hour working day, using a sample volume of approximately 1 milliliter. Because of the automated nature of the analysis, elements in addition to chlorine are determined, when present. These include fluorine, bromine, iodine and sulfur. U.S. National Bureau of Standards (NBS) and U. S. Environmental Protection Agency (EPA) Standard Reference Materials are routinely analyzed for quality assurance purposes. The results of our analyses of these materials for certified elements is discussed as well as results for other non-certified elements observed in the standard materials.     

Analytical properties of di(2-pyridyl)methylene 2-furoylhydrazone and spectrophotometric determination of trace amounts of iron

Summary The synthesis and analytical properties of di(2-pyridyl) methylene 2-furoylhydrazone (DPFH) are described. The solubility, spectral characteristics, andpK values are reported, as well as the absorptivity of metal chelates formed. The reaction between iron and DPFH has been studied by spectrophotometry. The green 12 iron: DPFH complex (=8.4×103l·-mole^–1·cm^–1 at 620 nm) is formed at pH 5.3–11.3. The effect of interferences has been studied and the method applied to the determination of iron in cement, with good results.

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Di-(2-pyridyl)methylen-2-furoylhydrazon als analytisches Reagens zur spektrophotometrischen Bestimmung von Eisenspuren

Zusammenfassung Synthese und analytische Eigenschaften von Di(2-pyridylmethylen-2-furoylhydrazon wurden beschrieben. Die Löslichkeit, die Spektraleigenschaften, diepK-Werte und die Absorptivität seiner Metall-Chelate wurden angegeben. Der grüne 12-Komplex mit Eisen bildet sich bei pH 5, 3-11, 3. Störfaktoren wurden untersucht und die Eisenbestimmung in Zement beschrieben.

     

Initial Growth of Functional Plasma Polymer Nanofilms

To gain deeper insights into the initial growth mechanism, with respect to functional group density and cross-linking, plasma polymer films (PPFs) were deposited from C₂H₄/NH₃ discharges. Keeping gas phase processes and electrical discharge conditions constant all over the deposition process, the mass deposition rate of the PPF was found to be initially lower and regularly increasing before reaching steady-state conditions after a film thickness of about 5 nm on metal oxide substrates. The first gradient nano-layer, i.e. the first 5 nm deposited, were observed to possess less amino functional groups and to be more cross-linked and thus more stable compared to the film prepared in steady state conditions, in which the uniform film comprises more amino functional groups, yet is less cross-linked and thus less stable. Due to its sticking probability, the substrate thus influences the initial deposition rate. Over plasma exposure time, the substrate becomes covered by an initial layer of PPF and the film-forming species are no longer deposited onto the pristine substrate but onto the already deposited organic polymer film. The preparation of the highly stable functional nanofilm, i.e. the initial PPF layer, can lead to new possible applications and fast deposition processes.     

Effect of hexyl substituent groups on photophysical and electrochemical properties of the poly[(9,9‐Dioctyluorene)−2,7‐diyl‐alt‐(4,7‐bis (3‐Hexylthien‐5‐Yl)−2,1,3‐Benzothiadiazole)−2′,2″‐diyl]

The effect of the presence of hexyl group in thiophene on the photophysical and electrochemical properties of poly[(9,9‐dioctyluorene)?2,7‐diyl‐alt‐(4,7‐bis(3‐hexylthien‐5‐yl)?2,1,3‐benzothiadiazole)?2′,2″‐diyl] (F8TBT) is investigated. The copolymers present electron donor–acceptor architecture and are synthesized by Suzuki coupling reaction. The UV/Vis spectra show absorption maximum in the wavelength range of blue and orange, which are associated with different segments of the polymer backbone. Addition of hexyl substituent groups has a positive effect on the molar absorptivity and increases the emission and absorption intensities due to fluorene and thiophene‐benzothiadiazole‐thiophene (TBT) units, although an increment in the bandgap is observed. Cyclic voltammetry study of the polymer films reveal irreversible reduction and oxidation processes of the TBT units in the polymer chain and the HOMO and LUMO energy levels suggest ambipolar character for the polymers, while the electrochemical bandgaps are consistent with the absorbance measurements. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1975–1982