Further development and optimization of a quartz tube atomizer for a gas chromatography — atomic absorption spectrometer system

A new quartz T-tube furnace design based on commercial heater modules was evaluated for the determination of organolead and organotin compounds. Furnace operating conditions for both packed and capillary column operation were optimized by multivariate analysis. Response reproducibility ranged from 1.8 to 3.9% relative standard deviation. Calculated limits of detection were 1.4–2.0 pg for Et₄Pb (as Pb) and 2.2–5.5 pg for Bu₄Sn (as Sn). The limits of detection after application of Savitsky-Golay smoothing were 1.1–1.2 pg for Et₄Pb (as Pb) and 2–3.7 pg for Bu₄Sn (as Sn).     

Kathodenstrahlpolarographische Bestimmung von Spurenelementen in Tetrachlorogolds?ure nach ionenaustausch-chromatographischer Trennung

Zusammenfassung Die kathodenstrahlpolarographische Bestimmung von Ni, Pb, Cu, Co, Fe, Mo, Te, Sn, Zn, Bi, Cd, Tl in Tetrachlorogoldsäure wird beschrieben. Die Nachweisgrenzen liegen im 10^–4%- bzw. 10^–5%-Bereich (Ni, Co, Mo). Die Spuren werden über einen Ionenaustauscher AG 1X8 untereinander und von der Matrix getrennt.

---

Cathode-ray polarographic determination of trace elements in tetrachloroauric acid after separation by ion exchange

A method is described for the cathode-ray polarographic determination of traces of Ni, Pb, Cu, Co, Fe, Mo, Te, Sn, Zn, Bi, Cd, Tl in H(AuCl₄). Gold is separated from the trace metals by absorption on the strongly basic anion-exchange resin AG 1X8. The detection limits are within the ranges of 10^–4% and 10^–5% ((Ni, Co, Mo).

     

Preconcentration and determination of Sn- and Pb-organic species in environmental samples by SPME and GC-AED

A new sample preparation and preconcentration technique – solid phase microextraction (SPME) – is reported for the application of several tinorganic compounds and tetrabutyllead in aqueous samples. The solvent-free procedure is rapid in comparison with liquid-liquid extraction or SFE but also sensitive. Analytical variables of the extraction such as adsorption and desorption time, stirring rate and temperature has been investigated. The determination has been performed by GC coupled with atomic emission detection (AED). After optimization of the conditions of SPME a calibration was realized on the basis of a multicomponent standard solution, prepared by ethylation of organotin salts directly in the sample using sodium tetraethylborate (NaBEt₄) without prior separation of the analytes from the matrix. The method permits preconcentration. Values of about 10 can be reached. A detection limit of 0.09 pg Sn and 0.08 pg Pb can be achieved under optimized conditions. The proposed procedure has been successfully applied to the analysis of organotin compounds in various slurry samples.     

Regioselective stannylmetalation of acetylenes in the presence of transition-metal catalyst

The reaction of terminal acetylenes with Bu₃SnMgMe, Bu₃SnA1Et₂, or (Bu₃Sn)₂Zn in the presence of various transition-metal catalysts provides vinylstannanes in good yields. Whereas copper catalysed stannylmagnesation of 4-benzyloxy-1-butyne gives (E)-4-benzyloxy-1-tributylstannyl-1-butene exclusively, palladium catalysed stannylzincation affords 4-benzyloxy-2-tributylstannyl-1-butene preferentially.     

Thermodynamics of ionic solvation inn-propanol from −50 to 50°C

Enthalpies of the solution of 1–1 electrolytes (LiBr, LiI, NaI, NaBPh₄, R₄NBr (R=Me, Et, Pr, Bu, Am), Et₄NCl, Bu₄NI, Ph₄PBr) in n-propanol were determined experimentally from–50 to 50°C. Standard enthalpies of solution of the electrolytes studied were determined on the basis of the extrapolation equation of Debye-Hueckel theory and taking ionic association into account. The reference salt Ph₄PBPh₄ was used to obtain the ionic solvation properties. Partial molar heat capacities of ions in propanol were calculated and compared to our previously reported data for ethanol. The changes in the ionic heat capacities with temperature are discussed.     

Coadsorption of Tetraalkylammonium Cations and Halide Anions on the Uncharged Surface of Mercury Electrode

The data on coadsorption of tetraethylammonium (Et₄N⁺), tetrapropylammonium (Pr₄N⁺), and tetrabutylammonium (Bu₄N⁺) cations with Cl^–, Br^–, and I^– anions on an uncharged mercury electrode are compared with the models of coadsorption in a common monolayer and two parallel layers. The second model is shown to be in best agreement with experimental isotherms. However, the least discrepancy between calculations and experimental results is obtained when coadsorption of mentioned cations and anions is described by the Frumkin isotherm for neutral molecules with certain effective adsorption parameters.     

Hydride generation-graphite furnace atomic absorption spectrometry: new prospects

Summary Methods are described for the interference free determination of As and Se in seawater as well as marine tissues and sediments based on the generation of AsH₃, and SeH₂ using NaBH₄ with subsequent trapping in a graphite furnace at 600° C. Calibration is achieved with simple aqueous working curves having sensitivities of 24±4 and 72±17 pg/0.0044 A for As and Se, respectively. Absolute detection limits of 30 pg As and 70 pg Se are estimated. Precision of determination is 2–3% for As and 5–10% for Se.

---

Graphitofen-AAS mit Hydriderzeugung: neue Entwicklungen

Zusammenfassung Verfahren werden beschrieben zur störungsfreien Bestimmung von As und Se in Meereswasser sowie marinen Geweben und Sedimenten, die auf der Erzeugung von AsH₃ und SeH₂ mit Hilfe von NaBH₄ und anschließender Graphitofen-AAS (600° C) beruhen. Die Eichung erfolgt mit einfachen Eichkurven, die mit wässrigen Lösungen hergestellt werden (Empfindlichkeit: 24±4 bzw. 72±17 pg/0,0044 A für As bzw. Se). Die absoluten Nachweisgrenzen liegen bei 30 pg As und 70 pg Se. Die Präzision beträgt 2–3% für As und 5–10% für Se.

     

Comparison of GC-ICP-MS and HPLC-ICP-MS for species-specific isotope dilution analysis of tributyltin in sediment after accelerated solvent extraction

This study describes a direct comparison of GC and HPLC hyphenated to ICP–MS determination of tributyltin (TBT) in sediment by species-specific isotope dilution analysis (SS-IDMS). The certified reference sediment PACS-2 (NRC, Canada) and a candidate reference sediment (P-18/HIPA-1) were extracted using an accelerated solvent extraction (ASE) procedure. For comparison of GC and LC methods an older bottle of PACS-2 was used, whilst a fresh bottle was taken for demonstration of the accuracy of the methods. The data obtained show good agreement between both methods for both the PACS-2 sediment (LC–ICP–IDMS 828±87 ng g^–1 TBT as Sn, GC–ICP–IDMS 848±39 ng g^–1 TBT as Sn) and the P-18/ HIPA-1 sediment (LC–ICP–IDMS 78.0±9.7 ng g^–1 TBT as Sn, GC–ICP–IDMS 79.2±3.8 ng g^–1 TBT as Sn). The analysis by GC–ICP–IDMS offers a greater signal-to-noise ratio and hence a superior detection limit of 0.03 pg TBT as Sn, in the sediment extracts compared to HPLC–ICP–IDMS (3 pg TBT as Sn). A comparison of the uncertainties associated with both methods indicates superior precision of the GC approach. This is related to the better reproducibility of the peak integration, which affects the isotope ratio measurements used for IDMS. The accuracy of the ASE method combined with HPLC–ICP–IDMS was demonstrated during the international interlaboratory comparison P-18 organised by the Comité Consultatif pour la Quantité de Matière (CCQM). The results obtained by GC–ICP–IDMS for a newly opened bottle of PACS-2 were 1087±77 ng g^–1 Sn for DBT and 876±51 ng g^–1 Sn for TBT (expanded uncertainties with a coverage factor of 2), which are in good agreement with the certified values of 1090±150 ng g^–1 Sn and 980±130 ng g^–1 Sn, respectively.     

Conductance of electrolytes in 1-propanol solutions from −40 to 25°C

Conductance data for solutions of LiCl, NaBr, NaI, KI, KSCN, RbI, Et₄NI, Pr₄NI, Bu₄NI, Bu₄NClO₄, n-Am₄NI, i-Am₄NI, n-Hept₄NI, Me₂Bu₂NI, MeBu₃NI, EtBu₃NI, i-Am₃BuNI, and i-Am₃BuNBPh₄ in 1-propanol at –40, –30, –20, –10, 0, 10, and 25°C are communicated and discussed. Evaluation of the data is performed on the basis of a conductance equation that includes a term in c^3/2. Single ion conductances at 25 and 10°C are determined with the help of transference numbers t _o ⁺ (KSCN/PrOH); the data are compared to data estimated by other methods. Ion-pair association constants and their temperature dependence are discussed in terms of contact and solvent separated ion pairs, and the role of non-coulombic forces is shown with the help of an appropriate splitting of the Gibbs energy of ion-pair formation.     

Speciation and GC retention indices of some organotin compounds in water

Analytical methods have been developed for the quantitative determination of Bu₄Sn, Bu₃Sn⁺, Bu₂Sn²⁺, BuSn³⁺, Me₃BuSn, Me₂Bu₂Sn, MeBu₃Sn, MeBuSn²⁺, Me₂BuSn⁺ and MeBu₂Sn⁺ in water. Organotin compounds are extracted from water with tropolone at 0.1 % in n-pentane, derivatized with n-pentylmagnesium bromide and determined by gas chromatography with flame photometric detection or flame ionization detection. Absolute detection limits are 0.05-0.12 ng and 1.2-13 ng as tin, respectively. The method was applied to the analysis of spiked tap-water containing 0.3-1000 ng cm^?3 of each of the organotin compounds.