Determination of sulfur in near-surface layers of materials by means of the32S(3He,p)34mCl nuclear reaction

The cross-sections of the³²S(³He, p)^34mCl nuclear reaction have been determined in the projectile energy region between 4.0 and 12.0 MeV with the aim of their use for the determination of sulfur in surface layers of materials by means of Charged Particle Activation Analysis (CPAA). The measured cross-sections indicate that the application of this reaction for the determination of ppm and sub-ppm concentrations of sulfur is possible depending on the matrix material (e.g. detection limit for S in GaAs is 2 ppm, whereas in Si 300 ppb).     

Determination of sulphur in fly ash by instrumental proton activation analysis

A method for the determination of sulphur in fly ash by instrumental proton activation analysis using the³⁴S/p,n/^34mCl reaction was developed. The 2128.5 keV and 3305.0 keV -rays of^34mCl /t=32.0 min/ were measured on a Ge/Li/ -spectrometer, shielded with a lead absorber to attenuate low energy -rays. Irradiation and measuring conditions were optimized. The detection limit for instrumental analysis is 0.3 to 1 mg g^–1 and the standard deviation is cca. 4% for a typical sample.     

The determination of sulphur in copper,nickel and aluminium alloys by proton activation analysis

The ³⁴S(p, n)^34mCl reaction induced by 13-MeV protons is used for the determination of sulphur in copper, nickel and aluminium alloys. The ^34mCl is separated by repeated precipitation as silver chloride. The results obtained were 3.08 ± 0.47, 1.47 ± 0.17 and <1μg g^-1 for copper, nickel and aluminium alloys, respectively.     

Charged particle activation analysis of phosphorus in biological materials

Charged particle activation analysis of phosphorus in biological materials using the³¹P (α,n)^34mCl reaction has been studied. Since^34mCl is also produced by the³²S (α,pn) and the³⁵Cl (α, α′ n) reactions, the thick-target yield curves on phosphorus, sulfur and chlorine were determined in order to choose the optimum irradiation conditions. As a result, it was found that the activation analysis for phosphorus without interferences from surfur and chlorine is possible by bombarding with less than 17 MeV alphas. The applicability of this method to biological samples was then examined by irradiating several standard reference materals. It was confirmed that phosphorus can readily be determined at the detection limit of 1 μg free from interferences due to the matrix elements.     

Determination of sulfur in steels by radiochemical neutron activation analysis with liquid scintillation counting

A method has been developed for the determination of low-level sulfur in steels by radiochemical neutron activation analysis. During sample irradiation, ³⁵S is produced by the ³⁴S(n,γ)³⁵S reaction. Irradiated steels are mixed with sulfur carrier and dissolved in HCl/HNO₃. Sulfur is reduced to H₂S by reaction with HI/H₃PO₂/HCl. The evolved H₂S is absorbed in dilute NaOH, which is mixed with scintillation cocktail for the measurement of ³⁵S by liquid scintillation counting. Sulfur carrier yield is determined by iodometric titration. Chlorine is also determined by RNAA in order to correct for ³⁵S produced via the ³⁵Cl(n,p)³⁵S reaction. Sulfur has been determined at mass fractions as low as ≈5 mg/kg in ultra-high-purity iron using this method.     

Cross-sections of 14 MeV neutron reactions producing short-lived nuclides

The cross-sections for the production of the short-lived nuclides:^26mAl,^197mAu,^136mBa,^79mBr,^139mCe,³⁴Cl,^167mEr,^114m3In,^114m2In,^38mK,^38mCl,²⁶Na,²⁰F,¹⁹²Re,^207mPb,^203mPb,^46mSc,^183mW,^90mZr obtained from (n, 2n), (n, n′), (n, alpha), (n,p) reactions using 14 MeV neutrons, were evaluated by the activation method. The experimental results of this work were compared with those obtained by other authors.     

Determination of lithium by reactor activation analysis using the reaction chain:6Li(n,t)4He;32S(t,n)34mCl

The occurrence, in a nuclear reactor, of the reaction chain:⁶Li(n,t)⁴He;³²S(t,n)^34mCl has been experimentally established. Experimentation for its application to the activation analysis determination of lithium has been carried out, and a radiochemical method for separation of^34mCl is presented. The sensitivity is 0.4 g for the following conditions; 15 min irradiation (thermal flux: 1.5·10¹³ n·cm^–2·s^–1); 30 min decay; 2,000 s measurement (semiconductor detector).     

Chemical consequences of3 5Cl(n,p)3 5 S transformation in alkali chloride matrix

A review on the studies of chemical consequences of recoil sulfur,^{3 5}S, produced by the nuclear reaction^{3 5}Cl(n, p)^{3 5} S in alkali chloride matrices is presented.     

Measurement of the δ34S value in methionine by double spike multi‐collector thermal ionization mass spectrometry using Carius tube digestion

Methionine is an essential amino acid and is the primary source of sulfur for humans. Using the double spike (³³S‐³⁶S) multi‐collector thermal ionization mass spectrometry (MC‐TIMS) technique, three sample bottles of a methionine material obtained from the Institute for Reference Materials and Measurements have been measured for δ³⁴S and sulfur concentration. The mean δ³⁴S value, relative to Vienna Canyon Diablo Troilite (VCDT), determined was 10.34 ± 0.11‰ (n = 9) with the uncertainty reported as expanded uncertainties (U). These δ³⁴S measurements include a correction for blank which has been previously ignored in studies of sulfur isotopic composition. The sulfur concentrations for the three bottles range from 56 to 88 µg/g. The isotope composition and concentration results demonstrate the high accuracy and precision of the DS‐MC‐TIMS technique for measuring sulfur in methionine. Published in 2010 by John Wiley & Sons, Ltd.     

Trace determination of silicon by heavy ion activation analysis

The Si(¹¹B, x)^34mCl and Si(¹⁹F, x)^44mSc reactions have been studied in order to work out their capabilities in determining traces of silicon. The first one has been tested with beam energies ranging from 19 to 27 MeV¹¹B; only Mg and Al have shown nuclear interferences and a 30-min 27 MeV¹¹B irradiation yields a 14 ng detection limit. The second reaction, investigated in between 35 and 46 MeV¹⁹F, yields a 16 ng detection limit with a 2 hrs 46 MeV¹⁹F irradiation; at that energy only Al and P present nuclear interferences.     

Revised δ34S reference values for IAEA sulfur isotope reference materials S‐2 and S‐3

Revised δ³⁴S reference values with associated expanded uncertainties (95% confidence interval (C.I.)) are presented for the sulfur isotope reference materials IAEA‐S‐2 (22.62 ± 0.16‰) and IAEA‐S‐3 (−32.49 ± 0.16‰). These revised values are determined using two relative‐difference measurement techniques, gas source isotope ratio mass spectrometry (GIRMS) and double‐spike multi‐collector thermal ionization mass spectrometry (MC‐TIMS). Gas analyses have traditionally been considered the most robust for relative isotopic difference measurements of sulfur. The double‐spike MC‐TIMS technique provides an independent method for value‐assignment validation and produces revised values that are both unbiased and more precise than previous value assignments. Unbiased δ³⁴S values are required to anchor the positive and negative end members of the sulfur delta (δ) scale because they are the basis for reporting both δ³⁴S values and the derived mass‐independent Δ³³S and Δ³⁶S values. Published in 2009 by John Wiley & Sons, Ltd.     

Donorstabilized Monometaphosphates and Phosphonates- Structure,Bonding, and Reactivity

Abstract

Previoudy we reported on the preparative use of donorstabilized monometaphosphates, Py.PO₂Cl and Py.PS₂Cl[¹]. ³P MAS investigations as well as X-ray single crystal analysis have been carried out. The isotropic chemical shift of the sulfur compound shows the typical downfield shift (106 ppm) with respect to the oxygen compound The chemical shift anisotropy gives additional information. The relative large spans ω (Py.PO₂Cl: 401 ppm, Py.PS₂Cl: 461 ppm) [²] reveal strong deviations from tetrahedral symmetry (ω = 0 ppm) in agreement with the structural data. The values of the skew parametem K (0.64 and 0.71 resp.) reflect the trend to axial symmetry (k = ± l). X-ray diffraction and NMR data suggest a structural model corresponding to a concentration of double bond character on the two P-X bonds. This model is consistent with the extremely short P-X bond length (1.449 Å and 1.921 Å rasp.) as well as the large P-X-P bond angles (126.4°and 123.7° resp.).     

Trace determination of boron,silicon and sulfur with oxygen-18 ion bombardment

In order to determine traces of boron, silicon and sulfur, B(¹⁸O, x)²⁷Mg, Si(¹⁸O, x)⁴³Sc and S(¹⁸O, x)⁴⁷V reactions have been investigated between 15 and 44MeV. At 34 MeV, only a few of the systematically identified nuclear interferences produce²⁷Mg and the detection limit is 30ng boron for a 10 minute irradiation with a 0.3μA·cm⁻² oxygen-18 beam. Silicon analysis has shown nuclear interferences from Al, P and K; interference-free detection limit is 80 ng silicon for an hour irradiation with a 0.4 μA·cm⁻² beam at 39 MeV. There is no nuclear interference for the sulfur determination and the detection limit is 5 ng sulfur for a 30 minutes irradiation with a 0.5 μA·cm⁻² beam at 39 MeV. Thus a selective and sensitive sulfur determination can be achieved.     

Experimental and computational studies on a new mixed ligand oxido–rhenium(V) compound

A mixed ligand oxido–rhenium(V) complex, [ReOS₃(HL)]Cl.H₂O ( 1p Cl.H₂O), with 3‐thiopentane‐1,5‐dithiolato (S₃) as a tridentate ligand and imidazolidinethione (HL) as an ancillary monodentate sulfur donor co‐ligand, has been synthesized. 1p Cl.H₂O has been characterized by spectral analyses. The X‐ray crystal structure of 1p Cl.H₂O shows that the complex contains a distorted square‐pyramidal “ReOS₄” core. The structural parameters agree with our optimized structure of 1p ⁺. Subsequently, the optimized structure was used to calculate systematically the relative stabilities of a sequence of oxido–Re(V) and the analogous oxido–Tc(V) complexes just by varying the donor sites (N, S, and O) on the tridentate ligand moiety in 1p ⁺. Electrochemical studies on 1p Cl.H₂O show an oxidative rhenium(VI)/ rhenium(V) couple at 1.561 V versus Ag/AgCl under controlled linear diffusion situation. Vibrational frequencies, electronic structures, and redox potential of 1p ⁺ have been calculated theoretically employing density functional theory (DFT) or time‐dependent‐DFT methods. The experimental findings are in excellent agreement with the computed results. The calculated redox potentials of the investigated oxido–Re(V) complexes and their oxido–Tc(V) counterparts are shown to correlate linearly with their respective chemical potential values.     

Precise isotope-ratio determination by CGC hyphenated to ICP– MCMS for speciation of trace amounts of gaseous sulfur,with SF<Subscript>6</Subscript> as example compound

Capillary gas chromatography coupled to an inductively coupled plasma mass spectrometer with multiple-collector detection (GC–ICP–MCMS) has been used to assess the precision and instrumental mass bias in sulfur isotope-ratio determination for the gaseous sulfur species SF₆. The isotopic composition of the compound was certified by the institute for reference materials and measurements (IRMM, Belgium) and is available as PIGS 2010. Integration of the peaks (peak half-width 1.4 s) was performed using a special peak-integration method based on definition of the integration area by assessment of a uniform isotope-ratio area within the chromatographic peak. Instrumental mass bias was determined to be approximately 12% per mass unit and proved to be stable in the concentration range measured. Replicate injections of 2, 10, 20, and 30 ng (as S) SF₆ diluted in argon gave precision for the ³²S/³⁴S ratio from 0.6% RSD for 2-ng injections to 0.03% RSD for 30-ng injections. The ³²S/³³S and ³³S/³⁴S isotope-ratio precision was better than 0.4% RSD for injections of 10 ng (as S) and higher. Detection limits were in the absolute pg range for all measured sulfur isotopes.     

Cyclotron production of34mCl for biomedical use

A method for simple and fast production of^34mCl as tracer for biomedical research work has been developed. Different target materials have been tested, the yield of^34mCl and co-produced contaminants examined, the fast chemical separation procedure developed and target system constructed.     

Determination of sulfur and selected trace elements in metallothionein-like proteins using capillary electrophoresis hyphenated to inductively coupled plasma mass spectrometry with an octopole reaction cell

The determination of sulfur in biologically relevant samples such as metalloproteins is described. The analytical methodology used is based on robust on-line coupling between capillary electrophoresis (CE) and octopole reaction cell inductively-coupled plasma mass spectrometry (ORC–ICP–MS). Polyatomic ions that form in the plasma and interfere with the determination of S at mass 32 are minimised by addition of xenon to the collision cell. The method has been applied to the separation and simultaneous element-specific detection of sulfur, cadmium, copper, and zinc in commercially available metallothionein preparations (MT) and metallothionein-like proteins (MLP) extracted from liver samples of bream (Abramis brama L.) caught in the river Elbe, Germany. Instrumental detection limits have been calculated according to the German standard procedure DIN 32645 for the determination of sulfur and some simultaneously measured trace elements in aqueous solution. For sulfur detection limits down to 1.3 g L^–1 (³⁴S) and 3.2 g L^–1 (³²S) were derived. For the other trace elements determined simultaneously detection limits ranging from 300 ng L^–1 (⁵⁸Ni) to 500 ng L^–1 (⁶⁶Zn, ⁵⁵Mn) were achieved. For quantification of sulfur and cadmium in a commercially available MT preparation under hyphenated conditions the use of external calibration is suggested. Finally, the need for proper sample-preparation technique will be discussed.     

Complementary molecular and elemental detection of speciated thioarsenicals using ESI-MS in combination with a xenon-based collision-cell ICP-MS with application to fortified NIST freeze-dried urine

The simultaneous detection of arsenic and sulfur in thioarsenicals was achieved using xenon-based collision-cell inductively coupled plasma (ICP) mass spectrometry (MS) in combination with high-performance liquid chromatography. In an attempt to minimize the ¹⁶O¹⁶O⁺ interference at m/z 32, both sample introduction and collision-cell experimental parameters were optimized. Low flow rates (0.25 mL/min) and a high methanol concentration (8%) in the mobile phase produced a fourfold decrease in the m/z 32 background. A plasma sampling depth change from 3 to 7 mm produced a twofold decrease in background at m/z 32, with a corresponding fourfold increase in the signal associated with a high ionization surrogate for sulfur. The quadrupole bias and the octopole bias were used as a kinetic energy discriminator between background and analyte ions, but a variety of tuning conditions produced similar (less than twofold change) detection limits for sulfur (³²S). A 34-fold improvement in the ³²S detection limit was achieved using xenon instead of helium as a collision gas. The optimized xenon-based collision cell ICP mass spectrometer was then used with electrospray ionization MS to provide elemental and molecular-based information for the analysis of a fortified sample of NIST freeze-dried urine. The 3σ detection limits, based on peak height for dimethylthioarsinic acid (DMTA) and trimethylarsine sulfide (TMAS), were 15 and 12 ng/g, respectively. Finally, the peak area reproducibilities (percentage relative standard deviation) of a 5-ppm fortified sample of NIST freeze dried urine for DMTA and TMAS were 7.4 and 5.4%, respectively. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effets de surface dans le dosage par activation neutronique du soufre

Surface effects in the determination of sulfur by neutron activation analysis Thermal neutron activation analysis leads to overestimated sulfur contents in some metals. This phenomenon was studied for samples of iron. It is attributed to ineffective chemical etching arising from dissolution of the metal through a surface layer which retains impurities, especially sulfur-35. Significant amounts of this isotope are produced at the surface through the ³⁵Cl(n, γ)³⁵S reaction. Experimental modifications which lead to the correct sulfur concentration are proposed.     

Sulfur trace determination in petroleum products by isotope dilution ICP-MS using direct injection by thermal vaporization (TV-ICP-IDMS)

An accurate, sensitive, and fast method for direct determination of total sulfur in petroleum products after thermal vaporization of an isotope-diluted sample was developed by using ICP-MS. ³⁴S-labelled dibenzothiophene spike was used for the isotope dilution step. The isotope-diluted sample was injected into a thermal vaporizer which was directly connected by a heated transfer line to the plasma torch. Sample transport was achieved by using a helium gas flow, and the isotope ratio ³⁴S/³²S was determined within seconds after injection. No other sample preparation other than the simple and fast isotope dilution step, which enables accurate and sensitive determination of sulfur at high sample throughputs, is necessary. Thus, this technique fits all needs for routine analyses. Validation of the TV-ICP-IDMS method was carried out by analyzing the certified gas oil reference materials BCR672 and BCR107. Comparison of results for noncertified low- and high-boiling samples, obtained from an ICP-IDMS microwave-assisted digestion method, also resulted in very good agreement. The low detection limit of 40 ng/g and the large dynamic range of TV-ICP-IDMS fulfill all necessities to allow analysis of sulfur in different petroleum products, e.g., even at the low concentration level of ‘sulfur-free’ gasoline.