Solid-Phase Microextraction of Aliphatic Alcohols Based on Polyaniline Coated Fibers

The efficiency of polyaniline (PANI), coated gold wire was investigated for use as a fiber for solid-phase microextraction (SPME). Aniline monomers were electropolymerized on gold wires by applying a constant current to an acetate buffer containing NaClO₄ as supporting electrolyte for 30 min. These fibers were used for the extraction of some aliphatic alcohols from gaseous samples. The results obtained proved the ability of PANI fiber for sampling organic compounds from gaseous samples. From this work, optimum conditions for preparation and conditioning of fibers and for the extraction of analytes from gaseous samples were obtained. Under optimum conditions, one fiber was used for several equivalent analyses and the relative standard deviations (RSD) were <7% (n=6). However, fiber to fiber reproducibility was <9% (n=6). This fiber is firm and durable and is simply prepared. Calibration graphs were linear in the range: 0.1–10 g mL^–1 for aliphatic alcohols; the detection limit range was 15–75 ng mL^–1 (S/N=3) using a flame ionization detector.     

Simple extraction of phencyclidine from human body fluids by headspace solid-phase microextraction (SPME)

Summary Phencyclidine (PCP) was found to be extractable by headspace solid-phase microextraction (SPME) from human whole blood and urine. Sample solutions were heated at 90°C in the presence of NaOH and K₂CO₃, and an SPME fiber was exposed in the headspace of a vial for 30 min. Immediately after withdrawal of the fiber, it was analyzed by gas chromatography with surface ionization detection (GC-SID). Recoveries of PCP were approximately 9.3–10.8% and 39.8–47.8% for whole blood and urine samples, respectively. The calibration curve for PCP showed good linearity in the range 2.5–100 ng mL^–1 whole blood and 0.5–100 ng mL^–1 urine. The detection limits were approximately 1.0 ng mL^–1 for whole blood and 0.25 ng mL^–1 for urine.     

Über die Gewinnung und Thermostabilität der Chalkogenate von Antimon und Wismut, 2. Mitt.: Gewinnung und Untersuchung der Thermostabilität von Wismuttellurit

Zusammenfassung Wismuttellurit-Trihydrat Bi₂(TeO₃)₃·3H₂O wurde hergestellt und sein Verhalten thermisch, thermogravimetrisch, chemisch sowie phasen-röntgenographisch studiert. Es wurde festgestellt, daß bei 175–192°C das Trihydrat in das Dihydrat übergeht, das bei 275–300°C eine monotrope Umwandlung erfährt. Bei weiterem Erhitzen erfolgt eine partielle Oxidation des Te(IV) zu Te(VI), begleitet von einem exothermen Effekt, der bei 348–366°C auftritt. Die vollkommene Entwässerung der Substanz tritt bei 480–500°C ein. Bei 525–600°C wird Te⁶⁺ wieder zu Te⁴⁺ reduziert und schmilzt das Wismuttellurit.

---

Preparation and thermostability of the chalkogenates of antimon and bismuth, II: Preparation and thermostability of bismuth tellurite

Bismuth tellurite—the tri-hydrate—has been prepared. By thermal, thermo-gravimetric, chemical, as well as phaseroentgenographic analysis, the behaviour of Bi₂(TeO₃)₃·3H₂O upon heating has been studied. It was found that at 175–192°C the tri-hydrate passes into the di-hydrate, which at 275–300°C undergoes a monotropic transformation. On further heating, a partial oxidation of Te(IV) to Te(VI) takes place, accompanied by an exothermal effect at 348–366°C. The complete desiccation of the substance takes place presumably at 480–500°C. At 525–600°C Te⁶⁺ is again reduced to Te⁴⁺ and the bismuth tellurite melts.

---

---

Mit 2 Abbildungen     

Thermal analysis of poly(2-methylpentamethylene terephthalamide)

Poly(2-methylpentamethylene terephthalamide) (Nylon M5T) is a new high temperature aromatic polyamide developed by Hoechst Celanese. In this paper thermal properties of Nylon M5T chips, as well as as-spun and drawn fibers were studied by DSC, DMA, hot stage microscopy and WAXS.T _g of the fully amorphous Nylon M5T is 143°C when measured by DSC;T _g increases with crystallinity to 151°C. The temperature dependence of the solid and melt specific heat capacities has also been determined. The heat capacity increase at the glass transition of the amorphous polymer is 103.9 J °C^–1 mol^–1.T _g by DMA for the as-spun fiber is 155°C, for a drawn fiber is 180°C. Three secondary transitions were observed by DMA in addition to the glass transition. These correspond to a local mode relaxation of the methylene groups at –120°C, onset of rotation of the amide-groups at –65°C and the onset of the rotation of the phenylenegroups (at 63°C). The crystallinity of Nylon M5T strongly depends on the rate of cooling from the melt. The isothermal crystallization data are melt temperature dependent: two-dimensional crystallization takes place when the samples are crystallized from higher melt temperatures, and this phase changes into a spherulitic structure during cooling to room temperature. Spherulitic crystallization occurs when lower melt temperatures are used. This polymer has three crystal forms as indicated by DSC, DMA and WAXS data. The crystal to crystal transitions are clearly visible when amorphous samples are heated in the DSC, or the DMA curves of as-spun fibers are recorded. It is experimentally shown that a considerable melting of the lower temperature crystal forms takes place during the crystal to crystal transitions. The equilibrium melting point as measured by the Hoffman-Weeks method, has been determined to be 339°C.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthday     

Sol-Gel Processing and Luminescent Properties of Rare-Earth Oxyfluoride Materials

Luminescent rare-earth oxyfluoride materials were prepared by a sol-gel method using trifluoroacetic acid as a fluorine source. Crystalline (La, Eu)OF powders and thin films were obtained by heating gels at typically 600–800°C. Transparent SiO₂-LaOF glass-ceramic thin films were also prepared by mixing the trifluoroacetate sols and silica sols, spin-coating on silica glass substrates and heating at temperatures 600–900°C. Eu³⁺ ions doped in the oxyfluoride materials exhibited a strong red ⁵D₀ ⁷F₂ emission (611 nm) by a charge-transfer (O^2–-Eu³⁺) excitation with ultra-violet radiation (265 nm). It was strongly suggested that the Eu³⁺ activators were preferentially incorporated into the crystalline LaOF phase in the SiO₂-LaOF glass-ceramics.     

Thermal decomposition of silver cyano complex and characterization its decomposition products by ETA,DSC, DTA and TG

It was found by DTA and TG that [Phenyl₂I][Ag(CN)₂] in the solid state is chemically stable on heating in argon up to 160°C. During heating to higher temperatures it decomposes, forming volatile products such as [Phenyl]I, [Phenyl]NC and (CN)₂ [1]. After heating the sample to 500°C metallic silver resulted. The volatile and intermediate solid products were analysed by IR-spectroscopy.It was found by means of DTA and ETA that an isophase reversible transition takes place when the sample is heated and cooled, not higher than 100°C. At heating higher than 100°C the sample melts (melting pointT _m=135°C). The enthalpy melting was determined by means of DSC (H=–28 kJ·mol^–1).By means of ETA the disorder degree of the final decomposition product was estimated. The value of the activation energy of radon diffusion in the temperature range 720°–500°C equals 32.6 kJ·mol^–1.Dedicated to Prof. I. N. Bekman Moscow State University at the occasion of his 50th birthday     

ZrO<Subscript>2</Subscript> and Cu/ZrO<Subscript>2</Subscript> Sol–Gel Materials Spectroscopic Characterization

Copper-doped zirconia (1% mol) and zirconia powders were prepared by the sol–gel process, using zirconium n-butoxide and copper nitrate as precursors. The resulting xerogels are nanocrystalline and exhibit different properties from the corresponding microcrystalline materials. The copper nitrate salt was dissolved and co-gelled in situ at the initial stage of the reaction. The properties of the resulting materials were studied by XRD, FTIR and UV-Vis. The as-prepared samples were amorphous and crystallized to the tetragonal zirconia phase at 400 °C. At temperatures higher than 600 °C, the monoclinic phase was also obtained. No evidence of discrete crystalline copper compounds was observed, consistent with good dispersion of the dopant. Several bands were observed by FTIR in the 4400–3000 cm^–1 region, which diminishes in intensity and shifted to higher wavenumbers with heating. The bandgap energy (E_g) was strongly modulated by the presence of the dopant and heating temperature, with increasing temperature leading to a corresponding decrease in E_g.     

Self-doped polyaniline as new polyaniline substitute for solid-phase microextraction

This work is a first study on extraction efficiency and thermal stability of nano-structured self-doped polyaniline (SPAN) as a coating of solid-phase microextraction (SPME) fibers. SPAN-based fibers were prepared using electrochemical deposition on platinum wires. The particle sizes of prepared nano-structure were in the range of 50–100 nm. Extraction properties of the fiber to 1,4-dioxane were examined using headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-flame ionization detection (GC-FID). The results have proved higher thermal stability of the proposed fiber compared to common PANI fiber. The SPAN coating was proved to be very stable at relatively high temperatures (up to 350 °C) with high extraction capacity and long lifespan (more than 50 times). Therefore, it can be a good substitute of polyaniline (PANI) as a SPME coating. The extraction procedure was optimized by selecting the appropriate extraction parameters including extraction time, extraction temperature, salt concentration, stirring rate and headspace volume. Calibration graph was linear in the concentration range of 1–100 ng mL⁻¹ (R² > 0.993) with detection limit of 0.1 ng mL⁻¹. Single fiber and fiber-to-fiber repeatability were lower than 6.0% and 10.4%, respectively. Different water samples were analyzed as real samples and good recoveries (98–120%) were obtained.     

Thermogravimetric studies of the synthesis of cas from gypsum, CaSo4·2H2O and phosphogypsum

Using a heating rate of 2°C min^–1, CaS reacts with oxygen in air from 700°C to form CaSO₄, with a complete conversion at 1100°C. Synthesis of CaS from the reaction between CaSO₄ containing compounds and carbon compounds in air would not be possible, as the carbon reacts from 600°C with oxygen in the air to give CO₂. Heating stoichiometric amounts of carbon and pure CaSO₄, synthetic gypsum or phosphogypsum in a nitrogen atmosphere, results in the formation of CaS from 850°C. Using a heating rate of 10°C min^–1, the formation of CaS is completed at 1080°C. Addition of 5% Fe₂O₃ as a catalyst lowers the starting temperature of the reaction to 750°C. Activation energy values at different fraction reaction values () differ between 340 and 400 kJ mol^–1. The relationship between the activation energy values and conversion () indicates that the reaction proceeds via multiple steps.     

Detection of ethanol in human body fluids by headspace solid-phase micro extraction (SPME)/capillary gas chromatography

Summary Ethanol has been found extractable from human whole blood and urine samples by headspace solid-phase micro extraction (SPME) with a Carbowax/divinylbenzene-coated fiber. After heating a vial containing the body fluid sample with ethanol, and isobutanol as internal standard (IS) at 70°C in the presence of (NH₄)₂SO₄, a Carbowax/divinylbenzene-coated SPME fiber was exposed in the headspace of the vial to allow adsorption of the compounds. The fiber needle was then injected into a middle-bore capillary gas chromatography (GC) port. The headspace SPME-GC gave intense peaks for both compounds; a small amount of background noises appeared, but did not interfere with the detection of the compounds. Recoveries of ethanol and IS were 0.049 and 0.026% for whole blood, respectively, and 0.054 and 0.085% for urine, respectively. The calibration curves for ethanol showed excellent linearity in the range of 80–5000 mg L^–1 for whole blood and 40–5000 mg L^–1 for urine; the detection limits for both samples were 20 and 10 mg L^–1, respectively. The data on actual determination of ethanol after the drinking of beer are also presented for two subjects.     

Liquid chromatographic–electrospray mass spectrometric determination of cyclosporin A in human plasma

A rapid, sensitive and selective liquid chromatography–mass spectrometry (LC–MS) assay has been developed for determination of cyclosporin A (CyA) in human plasma; cyclosporin B (CyB) was used as internal standard (IS). The method utilized a combination of a column-switching valve and a reversed-phase symmetry column. The mobile phase was a 25:75 (v/v) mixture of 10% aqueous glacial acetic acid and acetonitrile. Running time per single run was less than 10 min. Sample preparation included C₈ SPE of human plasma spiked with the analyte and internal standard, evaporation of the eluate to dryness at 50°C under N₂ gas, and finally reconstitution in the mobile phase. Detection of cyclosporin A and the IS was performed in selected ion-monitoring mode at m/z 601.3 and 594.4 Da for CyA and IS, respectively. Quantitation was achieved by use of the regression equation of relative peak area of cyclosporin to IS against concentration of cyclosporin. The method was validated according to FDA guideline requirements. The linearity of the assay in the range 5.0–400.0 ng mL^–1 was verified as characterized by the least-squares regression line Y=(0.00268±1.9×10^–4)X+(0.00078±1.8×10^–3), correlation coefficient, r=0.9986±1.1×10^–3 (n=48). Intra and inter-day quality-control measurements in the range 5.0–350.0 ng mL^–1 revealed almost 100% accuracy and 9% CV for precision. The mean absolute recovery of CyA was found to be 84.01±9.9% and the respective relative recovery was 100.3±9.19. The limit of quantitation (LOQ) achieved was 5 ng mL^–1. Eventually, stability testing of the analyte and IS in plasma or stock solution revealed that both chemicals were very stable when stored for long or short periods of time at room temperature or –20°C.     

Synthesis and applications of poly(acryl<Emphasis Type="Italic">p</Emphasis>-aminobenzenesulfonamideamidine-<Emphasis Type="Italic">p</Emphasis>-aminobenzenesulfonylamide) chelating fiber for pre-concentrating and separating trace Bi(III), Hg(III), Au(III) and Pd(IV) from solution samples

Poly(acrylp-aminobenzenesulfonamideamidine-p-aminobenzenesulfonylamide) chelating fiber containing "S", "N", and "O" elements was synthesized from polyacrylonitrile fiber and p-aminobenzene sulfonamide and used to enrich and separate trace Bi(III), Hg(III), Au(III), and Pd(IV) ions from wastewater and ore sample solution. The enrichment acidity, flow rate, elution conditions, reuse, interference ions, saturated adsorption capacity, constant of adsorption rate, analytical accuracy, and actual samples on chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry (ICP-OES) with satisfactory results. Solutions of 100 ng mL^–1 of Bi(III), Hg(III), Au(III), and Pd(IV) ions can be enriched quantitatively by this chelating fiber at a rate of 1.0 mL min^–1 at pH 4 and desorbed quantitatively with 20 mL of 0.25 M HCl and 2% CS(NH₂)₂ solution at 50 °C (with recovery 97%). When the chelating fiber was reused for 20 times, the recoveries of the analyzed ions enriched by the fiber were still over 95% (except for Hg(III)). One thousand-fold excesses of Mn²⁺, Ca²⁺, Zn²⁺, Mg²⁺, Fe³⁺, Cu²⁺, Ni²⁺, Al³⁺, and Ba²⁺ ions and thousands-fold excesses of Na⁺ and K⁺ cause little interference in the pre-concentration and determination of the analyzed ions. The saturated adsorption capacity of Bi(III), Hg(III), Au(III), and Pd(IV) was 4.850×10^–4, 3.235×10^–4, 2.807×10^–4, and 3.386×10^–4 mol g^–1, respectively. The constants of adsorption rate were 0.409 min^–1 for Bi, 0.122 min^–1 for Hg, 0.039 min^–1 for Au, and 0.080 min^–1 for Pd. The relative standard deviations (RSDs) for the enrichment and determination of 10 ng mL^–1 Bi(III), Hg(III), Au(III), and Pd(IV) were lower than 2.3%. The results obtained for these ions in actual samples by this method were basically in agreement with the given values with average errors of less than 1.0%. FT-IR spectra shows that the existence of –SO₂–Ar, –H₂N–Ar, O=C–NH–, HN=C–NH–, and –HN–SO₂ functional groups are verified in the chelating fiber. From the FT-IR spectroscopy, we can see that Hg(III), Au(III), and Pd(IV) are mainly combined with nitrogen and sulfur (or oxygen), and Bi(III) is mainly combined with nitrogen (or oxygen) of the groups to form a chelating complex.     

Ionization constants of aqueous ammonia from 25 to 250°C and to 2000 bar

The ionization constant of ammonia has been determined by conductivity measurements and found to vary from 1.77×10^–5 at 25°C to 1.3×10^–6mol-kg^–1 at 250°C. The pressure effect to 2000 bar has been measured and the ratio K₂₀₀₀/K₁ is 6.8 at 25°C and 11 at 250°C. The standard molar volume change for the ionization at 1 bar, V ₁ ^o , changes from –28.8 at 25°C to –67 cm³-mol^–1 at 250°C.     

Preparation of Lead Zirconate Titanate Ceramic Fibers by Sol-Gel Method

PZT fibers with the nominal composition of Pb(Zr_0.53Ti_0.47)O _x have been successfully drawn by the sol-gel techniques. Ti(O·i–C₃H₇)₄, Zr(O·n–C₄H₉)₄, and Pb(O₂C₈H₁₅)₂ were used as the starting materials. The rheological conditions for continuous gel fiber drawing were determined. Thermal and microstructural evolutions of gel fibers were investigated by X-ray diffraction and Fourier-transform infrared spectroscopy. Perovskite crystalline fibers without breakage were obtained by a two-stage heat treatment on the gel fibers up to 600°C in air. Bending strength of the fibers decreases with the increase of the fiber diameter and is ranged from 10 to 30 MPa.     

Low-temperature electrothermal vaporization of thenoyltrifluoroacetone complex of Sc(III) and Y(III) for sample introduction in an inductively coupled plasma atomic emission spectrometry,and their determination in biological samples

A new method for inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of trace Sc and Y, based on gaseous compound introduction into the plasma as their thenoyltrifluoroacetone (TTA) complexes by electrothermal vaporization was developed. Using the reagent TTA as chemical modifier can not only enhance the analytical signals, but also reduce the vaporization temperature. At a temperature of 1,000 °C the trace Sc and Y can be vaporized completely into ICP. The factors affecting the formation of the chelate and its vaporization behavior, such as drying time, vaporization temperature/time, reaction medium and the amount of TTA, were investigated in detail. Under the optimized conditions (drying temperature/time 100 °C/10 s, vaporization temperature/time 1,000 °C/4 s), the limits of detection for Sc and Y were 19 pg and 34 pg (3), respectively, and the relative standard deviations for Sc and Y were 4.2% (c _Sc=0.2 g mL^–1; n=7) and 2.6% (c _Y=0.5 g mL^–1; n=7). The linear ranges of the calibration graphs cover three orders of magnitude. The method was applied to the analysis of the biological reference materials (GBW 07602, bush branches and leaves; GBW 07604, poplar leaves), and the results obtained were in good agreement with the certified values.     

Synthesis and Electrical Properties of Lithium Metazirconate

Lithium metazirconate Li₂ZrO₃ with a monoclinic lattice is synthesized; the lattice parameters are: a = 0.5432 nm, b = 0.5427 nm, c = 0.903 nm, = 112.72°, and Z = 4. The conductivity of both the stoichiometric compound and samples rich or deficient in Li₂O near this composition is determined. The conductivity of the synthesized compound reaches 0.029 S cm^–1 at 600°C. The activation energy for the high-temperature segment is 13.8 kJ mol^–1. An abnormal behavior (abrupt jump) of the temperature dependence of the conductivity at 430°C is discovered and attributed to a phase transition. The change in the structure in this temperature domain (400 to 500°C) is corroborated by the high-temperature X-ray analysis.     

Kinetic Determination of Mercury(II) at Trace Level from Its Catalytic Effect on a Ligand Substitution Process

A catalytic kinetic method (CKM) is presented for the determination of mercury(II) based on its catalytic effect on the rate of substitution of N-methylpyrazinium ion (Mpz⁺) onto hexacyanoferrate(II). The progress of the reaction was monitored spectrophotometrically at 655 nm by registering the increase in absorbance of the product [Fe(CN)₅(Mpz]²⁻ under the reaction conditions: 5 × 10⁻³ mol L⁻¹ [Fe(CN)₆]⁴⁻), 5 × 10⁻⁵ mol L⁻¹ [Mpz⁺], T = 25.0 ± 0.1°C, pH 5.00 ± 0.02 and ionic strength, I = 0.1 mol L⁻¹ (KNO₃). Quantitative rate data at specified experimental conditions showed a linear dependence of the absorbance after fixed time A _t on the concentration of mercury(II) catalyst in the range 20.06–702.1 ng mL⁻¹. The maximum relative standard deviations and percentage errors for the determination of mercury(II) in the range of 20.06–200.6 ng mL⁻¹ were calculated to be 1.7 and 2.7% respectively. The detection limit was found to be 7.2 ng mL⁻¹ of mercury(II). Accuracy (expressed in terms of recoveries) was in the range of 98–103%. Figures of merit and interference due to many cations and anions was investigated and discussed. The applicability of the method was demonstrated by determining the mercury(II) in different synthetic samples and confirming the results using atomic absorption spectrophotometry. The proposed method allowed determination of mercury(II) in the range 20.06–702.1 ng mL⁻¹ with very good selectivity and an output of 30 samples h⁻¹.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 654–661.Original English Text Copyright © 2005 by Surendra Prasad.This article was submitted by the author in English.     

Study of the fluorite–pyrochlore–fluorite phase transitions in Ln<Subscript>2</Subscript>Ti<Subscript>2</Subscript>O<Subscript>7</Subscript> (Ln=Lu,Yb, Tm)

The ordering processes in Ln₂Ti₂O₇ (Ln=Lu, Yb, Tm) are studied by X-ray diffraction, thermal analysis, infrared absorption (IR) spectroscopy, and electrical conductivity measurements. The coprecipitation method followed by freeze-drying was used for Ln₂Ti₂O₇ synthesis. The region of low-temperature fluorite phase existence is 600 °C<T<740 °C. The low-temperature fluorite–pyrochlore phase transition in Ln₂Ti₂O₇ takes place at ~740–800 °C. Ln₂Ti₂O₇ (Ln=Lu, Yb, Tm) have the structure of disordered pyrochlore with antisite Ln–Ti defects at 800 °C<T<1,100 °C.The high-temperature pyrochlore–fluorite transformation takes place in Tm₂Ti₂O₇, Yb₂Ti₂O₇, and Lu₂Ti₂O₇ in air at T>1,600 °C. The conductivity values are 5·10^–3 S/cm for Tm₂Ti₂O₇, 6·10^–3 S/cm for Yb₂Ti₂O₇, and 10^–2 S/cm for Lu₂Ti₂O₇ at 740 °C. This order–disorder transition leads to a 2 orders of magnitude conductivity growth and a 10–30 times permittivity increase in Ln₂Ti₂O₇ samples obtained at 1,700 °C.Presented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, 10–12 April 2003     

Application of tertiary amines for arsenic and selenium signal enhancement and polyatomic interference reduction in ICP-MS analysis of biological samples

Water soluble tertiary amines enhance signals and decrease polyatomic chloride interferences in the direct inductively coupled plasma – mass spectrometric (ICP-MS) determination of As and Se in biological samples. Preliminary experiments with amine concentrations and nebulizer flow rates produced element and interference signal intensity changes. Arsenic and Se ICP-MS determination parameters have been optimized by a simplex procedure with amines in an argon plasma or without amines but with addition of N₂ to the Ar. Variables include RF (radio frequency) power, nebulizer gas flow rate, intermediate gas flow rate, and amine concentration or nitrogen gas flow rate. Detection limit, minimization of polyatomic ion intensities, and reproducibility have been evaluated as reponse factors. The signal enhancement and element-to-molecular interference ratios differ to some extent with analyte intensity optimum operating conditions. The detection limits with addition of nitrogen (16 pg mL^–1 for As and 180 pg mL^–1 for Se) or of amines (8 pg mL^–1 for As and 120 pg mL^–1 for Se) and the extent of chloride interference minimization were compared. Amines addition was more beneficial. Biological standard reference materials and food and fecal samples were analyzed following different sample dissolution procedures.     

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.