Direct gas chromatographie determination of organotins as halide forms [Détermination des organoétains par injection directe sous forme d'halogénures et chromatographie gazeuse]

cited By 6International audienceA critical review of procedures for the determination of organotin compounds in standards and natural samples (waters, sediments, biological matrices) without derivatization step has been carried out from 47 references. After acidification and extraction from sample, organotins as halides are directly injected into the gas chromatograph (GC). Operating conditions have been reported and compared for each experimental step. The stability of organotin halides in solution and during the chromatographic analysis has been described. Several detections methods have been used by the authors. Flame photometry (FPD) has been submitted to particular examination. Detection limits have been compared according to the type of detection. Finally, the abilities and limits of the direct chromatographie determination of organoiin halides have been established from the bibliography. © 1995 Elsevier, Paris

LJ Les plans d'experiences en spectrometrie d'absorption atomique : Application à la determination du selenium

International audienceThe optimisation of the determination of inorganic selenium by Hydride Generation/Quartz Furnace- Absorption Atomic Spectrometry was performed considering 12 operating parameters. The research of the influent factors was carried out from two experimental designs 24. Their realisation has allowed the determination of the operating conditions of the hydridation (HCI concentration and NaBH4 solution flow rate), the adjustment of the gas flow rates (He, O2 and H2) and consequently the control of the whole analytical process. The optimized method for the determination of inorganic selenium has been found to be sensitive, repeatable and reliable with absolute detection limits lower than 2 ng and relative standard deviations evaluated from 6 determinations ranging from 3 to 6%. © EDP Sciences, Wiley-VCH

VUV and photoelectronic spectra of methylstannane. Theoretical and experimental approach

cited By 3International audienceThe vacuum ultraviolet (VUV) and photoelectron spectra of SnH3CH3 were recorded between 6.20 and 11.28 eV and between 8 and 17 eV, respectively. Spectra were interpreted using ab initio CI calculations. The photoelectron spectrum confirmed the low SnC bond energy. The first two ionization potentials (IP) observed were attributed to the ionization of the a1 (10.65 eV) and e orbitals (11.15 and 11.60 eV, split by the Jahn-Teller effect), thereby showing an inversion of IPs compared with ethane. Similarly, the first two bands of the VUV spectrum (at 7.04 and 7.72-8.16 eV) were attributed to a1 and e transitions towards the Rydberg s orbital. A splitting of the same order of magnitude as that of the photoelectron spectrum could be noted in the E state. Observed transitions between 8.65 and 10 eV showed a strong interaction between the Rydberg p MO and the σ*SnC antibonding orbital. Primarilyvalence transitions were encountered beyond 10 eV. © 1987

Theoretical and experimental study of the vacuum ultraviolet spectrum of tetrasubstituted tin derivatives SnCl4 and Sn(CH3)4

cited By 5International audienceThe vacuum ultraviolet spectra of two tetrasubstituted tin derivatives (SnCl4 and Sn(CH3)4) have been recorded down to 110 nm. Ab initio CI calculations led to a satisfying interpretation of the electron and photoelectron spectra. The first two bands of SnCl4, at 201 and 163 nm, are attributed to (n → σ and σ → σ) valence transition, while the first band of Sn(CH3)4, at 186 nm, presents a pure Rydberg character, as in the case of SnH4. The rest of the spectrum can be attributed to Rydberg transitions mixed with valence states to varying extents. © 1987

The vacuum ultraviolet spectrum of stannane

cited By 9International audienceThe vacuum UV spectrum of SnH4 has been recorded up to 110nm (12.26 eV). This spectrum has been interpreted by ab initio calculations (SCF + CI), using a relativistic pseudopotential to describe the core electrons of the tin atom. The spectrum consists of a broad band composed of three maxima (at 8.73, 9.53 and 11.33 eV). The transition below 9.50 eV have been attributed to transitions to diffuse Rydberg states (6s and 6p). The other bands are due essentially to valence transitions. © 1986

Pressurised solvent extraction for organotin speciation in vegetable matrices

cited By 21International audienceThe evaluation and optimization of a specific procedure based on pressurized solvent extraction (PSE) that is suitable for monitoring organotin content in vegetables was reported. In ASE, solvents were used at elevated temperatures and pressures to increase the rate and efficiency of the extraction process. The influence of the pressure and the temperature of the PSE on the quantitativity of the process and on species preservation was evaluated using the experimental design methodology. COmparison with SLE comfirmed that PSE is an interesting tool for vegetable analysis considering the satisfactory OTC preservation and repeatability obtained for a relatively short extraction duration

Physico-chemical approach to study organotin sorption-desorption during solid-phase microextraction

International audienceSolid-phase microextraction (SPME) has become a real alternative to liquid-liquid extraction in the field of speciation of organometallic compounds. Despite the high performance of this preconcentration technique, matrix effects in natural samples can affect the analytical precision. In order to understand the origin of these disturbances and control the extraction step as best as possible, the sorption-desorption behaviour of organotins was studied. In the first part, this paper discusses the analytical problems encountered in the daily use of SPME due to the particular problems observed for phenyltins. The sorption profile of these compounds was modelled using experimental design methodology to confirm the first-order kinetics. Desorption of the compounds was also observed after a given time and could not be attributed to competition between organotin compounds. In the same way, butyl- and phenyltins were studied in the presence of humic substances, which acted as representatives of organic matter found in natural samples. These substances drastically decrease the extraction yields, but do not affect the sorption profile of butyl- and phenyltins. © 2003 Elsevier Science B.V. All rights reserved

Fate of organotin compounds in the soil – plant system: soil persistence, plant accumulation and toxicity

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Development of the extraction method for the simultaneous determination of butyl-, phenyl- and octyltin compounds in sewage sludge

cited By 21International audienceThe toxicity and bioaccumulation of organotin compounds (OTCs) led to the development of sensitive and selective analytical methods for their determination. In the past much attention was assigned to the study of OTCs in biological samples, water and sediments, coming mostly from marine environment. Little information about OTCs pollution of terrestrial ecosystems is available. In order to optimise the extraction method for simultaneous determination of butyl-, phenyl- and octyltin compounds in sewage sludge five different extractants (tetramethylammonium hydroxide, HCl in methanol, glacial acetic acid, mixture of acetic acid and methanol (3:1), and mixture of acetic acid, methanol and water (1:1:1)), the presence or not of a complexing agent (tropolone), and the use of different modes of extraction (mechanical stirring, microwave and ultrasonic assisted extraction) were tested. Extracted OTCs were derivatised with sodium tetraethylborate and determined by gas chromatography coupled with mass spectrometer. Quantitative extraction of butyl-, phenyl- and octyltin compounds was obtained by the use of glacial acetic acid as extractant and mechanical stirring for 16 h or sonication for 30 min. The limits of detection and quantification for OTCs investigated in sewage sludge were in the ng Sn g-1 range

Vacuum ultraviolet and photoelectron spectra of dimethyl- and trimethyl-stannane

cited By 1International audienceThe vacuum ultraviolet spectra of dimethyl- and trimethyl-stannane between 220 and 110 nm are reported. Comparison of the spectroscopic data (photoelectron and vacuum UV) for compounds of general formula SnHn(CH3)4-n have been used to reveal the effects of methylation on the stability of radical ions and the first Rydberg states. A comparison with results for the corresponding alkane, silane and germane series reveals a progressive increase in the energy of the valence electrons as the atomic number of the central atom increases. © 1989