Detector comparison for sulfur and chlorine detection with laser induced breakdown spectroscopy in the near-infrared-region

Laser-induced breakdown spectroscopy has been employed for the investigation of the sulfur and chlorine content of building materials. Both, chloride and sulfate ions are major damaging species affecting the stability and lifetime of a structure. Chlorine and sulfur are mostly detected in the VUV and the NIR. In case of building materials the main elements like calcium or iron have many strong spectral lines over the whole spectral range, so that trace elements can only be detected in spectral windows unaffected from these lines. With regard to a preferably simply, robust against dust and vibrations and portable setup only the NIR spectral features are used for civil engineering applications.

Most detectors, mainly CCD cameras have rapidly decreasing quantum efficiency in the NIR. Also the quantum efficiency of the photocathode of CCD-Detectors with image intensifier is decreasing in the NIR. Different CCD-detectors were tested with respect to high quantum efficiency and high dynamic range, which is necessary for simultaneous detection of weak spectral lines from trace elements and intense spectral lines from main elements.

The measurements are made on reference samples consisting of cement, hydrated cement, cement mortar and concrete with well-defined amounts of the trace elements. Experimental conditions are chosen for an optimum intensity of the trace element spectral lines. The detector systems are compared by limit of detections and the signal to noise ratio.     

The use of thermal analysis in the approximate determination of the cement content in concrete

Thermal analysis was first used to investigate the pattern of dissociation of hydrated ordinary Portland cement. Portlandite (Ca(OH)₂) decomposes at about 500°C. This was confirmed by kinetic calculations. Thermal analysis was then performed to establish the effect of varying the cement content on the percent mass loss associated with the decomposition of Ca(OH)₂ in cement mortar cured for 28 days. An increasing relation was obtained. Standard concrete cubes were then prepared with cement contents ranging from 200 to 450 kg m^-3. The loss in mass on heating, up to 750°C, of concrete samples cured for 28 days was then related to the cement content in concrete. The relation obtained was tested for concrete cubes of known cement content and found to be in better agreement than the results obtained by conventional chemical analysis. This method can be used for an approximate determination of the cement content in concrete. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of Chlorine and Chlorine Dioxide in Air with Semiconductor Sensors

The parameters of sensors for the determination of chlorine and chlorine dioxide in air in static and kinetic measurement modes were studied. A photocolorimeter was used for sensor calibration. It was show that the photocolorimeter can be calibrated for chlorine dioxide trace concentrations in air below 4 mg/m³.     

Chlorine detection in cement with laser-induced breakdown spectroscopy in the infrared and ultraviolet spectral range

A significant parameter to monitor the status of concrete buildings like bridges or parking garages is the determination of the depth profile of the chlorine concentration below the exposed concrete surface. This information is required to define the needed volume of restoration for a construction. Conventional methods like wet chemical analysis are time- and cost-intensive so an alternative method is developed using laser-induced breakdown spectroscopy (LIBS). The idea is to deploy LIBS to analyze drill cores by scanning the sample surface with laser pulses. Chlorine spectral lines in the infrared (IR) and ultraviolet (UV)-range were studied for chlorine detection in hydrated cement samples. The excitation energies of these spectral lines are above 9.2 eV. Hence high plasma temperatures and pulse energies in the range of some hundred millijoules are needed to induce sufficient line intensity levels at the required working distance. To further increase the line intensity and to lower the detection limit (LOD) of chlorine a measuring chamber is used where different ambient pressures and gases can be chosen for the measurements. The influences on the line intensity for pressures between 5 mbar and 400 mbar using helium as process gas and the influence of different laser burst modi like single and collinear double pulses are investigated. For the first time a LOD according to DIN 32 645 of 0.1 mass% was achieved for chlorine in hydrated cement using the UV line 134.72 nm.     

Optimization of cementitious composite for heavyweight concrete preparation using conduction calorimetry

The present work investigates the hydration heat of different cement composites by means of conduction calorimetry to optimize the composition of binder in the design of heavyweight concrete as biological shielding. For this purpose, Portland cement CEM I 42.5 R was replaced by a different portion of supplementary cementitious materials (blast furnace slag, metakaolin, silica fume/limestone) at 75%, 65%, 60%, 55%, and 50% levels to obtain low hydration heat lower than 250 j g^?1. All ingredients were analyzed by energy dispersive X-ray fluorescence (EDXRF) and nuclear activation analysis (NAA) to assess the content of major elements and isotopes. A mixture of two high-density aggregates (barite and magnetite) was used to prepare three heavyweights concretes with compressive strength exceeding 45 MPa and bulk density ranging between 3400 and 3500 kg m^?3. After a short period of volume expansion (up to 4 h), a slight shrinkage (max. 0.3°/°°) has been observed. Also, thermophysical properties (thermal conductivity, volumetric specific heat, thermal diffusivity) and other properties were determined. The results showed that aggregate content and not binder is the main factor influencing the engineering properties of heavyweight concretes.

     

Calorimetric Study of Frost Attack During Cement Hardening

This report deals with practical and experimental studies of the effects of frost attack on hardening cement stone and concrete. The basic component of concrete, cement stone, is a typical capillary-porous material formed from solid, liquid and gaseous phases. The level of knowledge on the effects of frost attack on cement stone and concrete hardening is insufficient, due to the complexity of the mechanisms of the accompanying effects. The values of internal pressures are determined among others by ice formation parameters, by the characteristics of the porous structure and the solid phase of the cement stone, and also by technological factors. The quantitative estimation of certain parameters is important for an approach to the understanding of the mechanism of frost attack and the choice of methods of its regulation for technological purposes. These are the temperature of pore liquid crystallization T _f, the degree of freezing F _d and the mass of ice I _m formed during freezing. Examples of changes in ice formation parameters on variation of some of the technological factors are given. This revised version was published online in August 2006 with corrections to the Cover Date.     

On the determination of sulfur by charged particle activation analysis

An analytical method is described for the determination of trace amounts of sulfur by charged particle activation analysis. The method consists of proton irradiation followed by a rapid radiochemical separation of the product nuclide,^34m Cl. This procedure has been applied to a number of pure metal samples which range in sulfur content from 0.3 to 30 ppm. All analyses were repeated several times to ensure consistent results and to better evaluate experimental detection limits and systematic errors. The results indicate that sulfur determinations can be performed at a concentration of less than 1.0 ppm. Activation curves are presented for the reactions S(d,x)^34mCl, S(p,x)^34mCl, and the interfering reaction³⁵Cl(p, pn)^34mCl. In memoriam.     

An evaluation of trace element analysis in the forensic investigation of fibre samples

The use of trace element analysis in the forensic examination of fibres has been investigated. Samples of both natural and synthetic fibres have been analysed to show that it is possible to both identify and discriminate between samples that would, by present methods, be considered indistinguishable. A number of wool garments of predetermined trace element composition were sent for wear for a period of nine months. The conditions and frequency of wear and cleaning were reported to enable their effect upon the trace element composition of these garments to be determined. The wool samples were analysed by both short (30 min) and long (50 hrs) irradiations in a reactor flux of about 10¹² n·cm⁻²·sec⁻¹. This permitted the concentrations of the elements such as sodium, chlorine, iodine, manganese, cobalt and chromium to be determined. Both sodium iodide and lithium drifted germanium detectors were used to measure the induced activity of the wool samples. The composition of a range of acrylic fibres from a variety of sources has also been examined using a sodium iodide detector. The concentrations of sodium chlorine, bromine, managese, copper, aluminium, titanium, indium and barium were determined in these samples.     

The Degradation of the Active Medium of an Argon Fluoride Discharge Lamp with a Noncorrosive Gas Mixture

The results of a spectroscopic study on the degradation of the active medium of an ArF electric-discharge lamp with the He–Ar–SF₆ working mixture (p 100 kPa) and pumped by a transverse space discharge are presented. Plasma radiation spectra were studied over the range 190–780 nm at different stages of degradation of the working mixture, and the dynamics of emission from the inert gases, as well as the products of sulfur hexafluoride degradation in the plasma, were determined. The ArF(B–X) emission band at = 193 nm was observed when the number of discharge pulses was 10³, whereas the quite effective formation of excited sulfur molecules, which decomposed producing emission bands in the spectral region of 260–550 nm, took place at n 10⁴.     

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.     

AQUEOUS AGGREGATES OF BACTERIOCHLOROPHYLL c AS A MODEL FOR PIGMENT ORGANIZATION IN CHLOROSOMES

Chlorosomes isolated from Chloroflexus aurantiacus were extracted with chloroform/methanol. The extract contained bacteriochlorophylls c and a and lipids, but was devoid of proteins. This crude extract spontaneously formed aggregates when a methanol solution was dispersed in aqueous buffer. The aggregates could be sedimented by ultracentrifugation and appeared in electron micrographs as stain-excluding bodies with diameters between 70 and 170 nm. The absorption spectrum is remarkably similar to that of intact chlorosomes with an absorption maximum of bacteriochlorophyll c at around 740 nm. The circular dichroism spectrum of the aggregate is also very similar to that of intact chlorosomes. A conservative (±) band centered at 740 nm confirms the highly aggregated state of bacteriochlorophyll c in both systems. Steady-state fluorescence studies showed that in the aggregate energy-transfer from bacteriochlorophyll c to a component emitting at 830 nm took place. When the aggregate was suspended in buffer saturated with 1-hexanol the 740 nm form of bacteriochlorophyll c was reversibly converted to a form with spectral properties resembling the monomer absorbing at 670 nm but still in an aggregated state. This form of bacteriochlorophyll c showed no circular dichroism signal.     

Measurement of concentration of chlorine attached to a stainless-steel canister material using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) in the single-pulse or orthogonal double-pulse configuration was performed for the measurement of the concentration of chlorine, which induces the occurrence of stress corrosion cracking (SCC), attached to stainless-steel (UNS S30403). The chlorine spectra were measured for samples sprayed with synthetic seawater with chlorine concentrations from 0.1 to 1.0 g/m². The chlorine emission intensity decreased between chlorine concentrations of 0.4 and 1.0 g/m² as determined in the single-pulse measurement. The chlorine concentration dependence of the chlorine emission intensity in the single-pulse configuration was unchanged even when the laser energy was set between 30 and 100 mJ. On the other hand, the chlorine emission intensity increased linearly versus chlorine concentration from 0.1 to 1.0 g/m² with the orthogonal double-pulse configuration. The results suggest that LIBS is promising for the inspection of the environmental condition for SCC initiation, which can occur when the chlorine concentration is greater than or equal to 0.8 g/m².     

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.     

Measurement of <Superscript>36</Superscript>Cl in nuclear wastes and effluents: Validation of a radiochemical protocol with an in-house reference sample

Summary ³⁶Cl is a beta-emitter with a very low specific activity. It is produced during the irradiation of nuclear fuel, in the reactor core of power plants, from neutron capture by stable ³⁵Cl that may be present at trace level in any part of the irradiated material. Due to its long half-life (T_1/2 = 3.01 ^. 10⁵ y), ³⁶Cl may be significant in impact assessment studies of disposal sites of nuclear wastes. Considering these different elements, the National Radioactive Waste Management Agency (Andra-France) requests information on the ³⁶Cl content of the waste packages destined to be stored at Andra sites. As for other halogens, the measurement of ³⁶Cl is a difficult analytical task in view of its potential losses during the different chemical steps and also because of the lack of international certified reference material needed to validate the chemical and measurement procedures. This paper describes the methodology processed to constitute an in-house solid reference sample with a known content of stable and radioactive chlorine. The original radiochemistry developed to extract ³⁶Cl from solid samples and purify it before a liquid scintillation counting is explained. The comparison of the results given by this radiochemical protocol and other methods allow its validation. The replication of the measurements on the constituted reference materials gives a repeatability around 8% at a confidence level of 95% that is very close to the calculated combined uncertainty value.     

RPLC retention of 1,ω-di(alkoxy)-polysulphides

Summary A simple and reliable method for routine measurement of ammonia in ambient air is described. It is based on the collection of ammonia on H₃PO₃-coated annular denuders and its subsequent derivatization withm-toluoyl chloride (MTC) in alkaline acetonitrile. The resultingm-toluamide is determined by reversed phase HPLC with UV detection at 230 nm. The limit of dotection is about 0.3g m^–3 for NH₃ in air samples collected at 151 min^–1 for one hour.     

Kilogram scale inverse vulcanization of elemental sulfur to prepare high capacity polymer electrodes for Li-S batteries

The synthesis of high content sulfur copolymers via the inverse vulcanization of elemental sulfur and 1,3-diisopropenylbenzene (DIB) on a one-kilogram scale is reported in a single step process. Investigation into the effects of temperature, reaction scale, and comonomer feed ratios on the inverse vulcanization process of S₈ and DIB were explored to suppress the Trommsdorf effect and enable large scale synthesis of these copolymers. The copolymers were then successfully used as the active cathode materials in Li-S batteries, exhibiting enhanced capacity retention and battery lifetimes (608 mAh/g at 640 cycles) at a C/10 rate. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 173–177     

ULTRAVIOLET QUANTUM YIELDS OF PHOTOPHOSPHORYLATION IN Halobacterium halobium*

Quantum yields of photophosphorylation in Halobacterium halobium were determined for ultraviolet spectral bands between 276 and 365 nm, and at 565 nm wavelength, based on integral spectral cell absorptance, bacteriorhodopsin-specific cell absorptance and the corresponding quantum dose rates. In the ultraviolet, there is an almost linear decline of the quantum yields of photophosphorylation from 365 to 276 nm wavelength, despite the peak absorption of bacteriorhodopsin at 280 nm. The cycling quantum yield for 276 nm excitation of bacteriorhodopsin was determined as 4.5 ± 1.8%, which is about one fourth of the value of 19% for solubilized bacteriorhodopsin. Threshold energy fluence rates of 20 W m^?2 for UV-B radiation typify the photophosphorylation as three orders less sensitive than the sensory UV-B avoidance response that needs 0.02 W m^?2 as the threshold. Thus, UV-B avoidance appears as the dominating strategy for survival of the archaic bacterium H. halobium, rather than possible photoenergetic use of UV-B radiation and photorepair of UV-damage.     

一种快速高选择性检测痕量癌胚抗原的共振散射光谱法

用10 nm的金纳米粒子标记单克隆癌胚抗原抗体制备了检测癌胚抗原（CEA）的共振散射光谱探针（Au-CEAAb）。在pH 6.8 的Na2HPO4- NaH2PO4缓冲溶液中及聚乙二醇-6000存在下, CEA与Au-CEAAb发生免疫反应聚集形成疏水性的、平均粒径为227.0 nm的免疫复合物微粒,并在321 nm、581 nm产生2个共振散射峰。随着癌胚抗原（CEA）浓度的增大,581 nm处的共振散射强度I581nm线性增加,其增加值△I581nm与CEA浓度在1.0～50.0 ng·mL-1范围内呈良好的线性关系,相应的回归方程、相关系数、检出限(3σ)分别为ΔI581nm=1.63 C +5.6、0.9940、0.52 ng·mL-1。该法简便、快速、灵敏且选择性好,用于检测人血清中癌胚抗原（CEA）,结果满意。     

Determination of pesticides in waters by capillary gas chromatography with atomic emission detection

Capillary gas chromatography with atomic emission detection (GC-AED) was successfully used to separate and quantify 14 pesticides (organochlorines, organophosphorus compounds and pyrethrins) in water samples after liquid-liquid extraction with ethyl acetate. Monitoring the emission lines for elements such as chlorine, bromine and sulfur ensures nearly specific chromatograms for these elements, and markedly increases selectivity. Calibration curves were obtained by plotting peak area versus concentration and the correlation coefficients relating to linearity were at least 0.999. Each chromatographic separation takes 21 min and, since two injections are necessary, it requires approximately 1 h to analyze one sample. The method shows a precision of 4.3-8.2% (RSD), depending on the compound. The application of liquid-liquid extraction with ethyl acetate led to recoveries from spiked samples ranging from 76 to 113%. The sensitivity and linearity for the elements chlorine, sulfur, nitrogen and phosphorus were checked under the optimized conditions at their customary emission wavelength. The sensitivity and linearity for these compounds decreased in the order (atom and emission wavelength) Cl (479 nm)>S (181 nm)>P (178 nm)>N (174 nm). A study of the GC-AED system's response to chlorine concentration in eight pesticide molecules was performed and a linear relationship was found with a correlation coefficient of 0.987.