Study of corrosion on copper strips by petroleum naphtha in the ASTM D-130 test by means of electronic microscopy (SEM) and energy dispersive X-ray (EDX)

Summary Corrosion in heat-engines has been attributed to some undesirable sulfur compounds present in petroleum naphthas, fuel-oils or gasolines. The corrosivity of these petroleum products is measured by means of the ASTM D-130 copper strip test, which is based on discoloration of a standard copper strip immersed into the petroleum products at 50°C for 3 h. The present paper studies various aspects of corrosivity of different sulfur compounds in petroleum naphthas by means of the ASTM D-130 test together with the electronic microscopy (SEM) and energy dispersive X-ray (EDX) techniques. These non-destructive techniques allow to know the strip corrosive morphology and to determine the sulfur concentration on this strip. Of the various types of sulfur compounds present in petroleum naphthas, the data show that elemental sulfur is corrosive to copper, but its corrosive level differes from naphtha to naphtha. Among the different mercaptans only ethyl-mercaptan presents corrosivity. The disulfides and sulfides tested are non-corrosive to copper.     

Study of corrosion on copper strips by mixtures of mercaptans, sulphides and disulphides with elemental sulphur in the ASTM D-130 test by means of electron microscopy (SEM) and energy dispersive X-ray (EDX)

Summary The corrosivity of sulphur compounds present in petroleum products is measured by means of the ASTM D-130 copper strip test, which is based on discoloration of a standard copper strip immersed into the petroleum products at 50°C for 3 h. This paper studies the influence that mercaptans, sulphides or disulphides exert on corrosion produced by elemental sulphur in synthetic naphtha in the ASTM D-130 test by means of scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. The synergistic effect of mercaptans on corrosion produced by elemental sulphur is an inverse function of the number of carbon atoms in linear mercaptans. For mercaptans with 6 carbon atoms corrosion activity follows the order: hexylmercaptan > cyclohexylmercaptan > thiophenol. In general, sulphides and disulphides decrease the corrosion produced by elemental sulphur. Among all the chemicals tested diphenyl disulphide is the best inhibitor of corrosion produced by elemental sulphur.     

Characterization of municipal solid waste incineration (MSWI) bottom ash by scanning electron microscopy and quantitative energy dispersive X-ray microanalysis (SEM/EDX)

Scanning electron microscopy (SEM) with energy-dispersive X-ray microanalysis (EDX) is frequently used for morphological and qualitative chemical characterization of different materials. The applicability of this method for phase identification, is, however, often underestimated. The application of SEM/EDX for the characterization of different phases in fresh and altered municipal-waste incinerator bottom-ash samples with high lateral resolution is presented. Polished thin sections were prepared from the samples, but fresh fracture surfaces were also used. The EDX analyses were performed by using the correction procedures of a conventional standardless ZAF correction, a peak-to-background ZAF correction, and a correction method for light-element analysis. Because of their highly reactive properties the bottom-ash SEM samples require a special method of preparation. The method facilitates nondestructive preparation of the sensitive bottom-ash alteration phases (e.g. cement phases, hydroxides, salts) and their microstructures.     

Characterization of municipal solid waste incineration (MSWI) bottom ash by scanning electron microscopy and quantitative energy dispersive X-ray microanalysis (SEM/EDX)

Scanning electron microscopy (SEM) with energy-dispersive X-ray microanalysis (EDX) is frequently used for morphological and qualitative chemical characterization of different materials. The applicability of this method for phase identification, is, however, often underestimated. The application of SEM/EDX for the characterization of different phases in fresh and altered municipal-waste incinerator bottom-ash samples with high lateral resolution is presented. Polished thin sections were prepared from the samples, but fresh fracture surfaces were also used. The EDX analyses were performed by using the correction procedures of a conventional standardless ZAF correction, a peak-to-background ZAF correction, and a correction method for light-element analysis. Because of their highly reactive properties the bottom-ash SEM samples require a special method of preparation. The method facilitates nondestructive preparation of the sensitive bottom-ash alteration phases (e.g. cement phases, hydroxides, salts) and their microstructures. Received: 18 August 2000 / Revised: 8 November 2000 / Accepted: 12 November 2000     

A comparison of scanning electron microscopy energy dispersive X-ray (SEM/EDX) and inductively coupled plasma optical emission spectrometry (ICP-OES) for provenance inferences of grog-tempered Bronze Age pottery

Pottery tempered with former pottery fragments (named grogs) is very common during the Bronze Age in the Cantabrian Cornice (North Spain). Grog tempered pottery from two coeval archaeological sites Santa Maria de Estarrona and Peracho are studied in order to establishes pottery provenance. Chemical analyses of pottery are used to discriminate locally from imported pottery under the assumption that different geological regions exhibit a distinctive chemical fingerprint. However, the pottery-maker usually transforms the original clay by tempering and prepares the material suitable for firing modifying the raw material chemical fingerprint. The problem increases when grogs are used as tempering agent. In these cases the chemical input is clearly contaminated with foreign materials making impossible to assign a source area. SEM-EDX has been applied to both the matrix and the different types of grog tempers and the results have been compared to the whole potsherd analysis performed by ICP-OES. Chemometric analysis of matrices enable to discriminate different raw materials that can be attributed to locally produced pottery. This chemical characterization of the matrices by SEM-EDX is more effective than the chemical composition determined for the whole potsherd by ICP-OES. The occurrence of grogs within grog tempers and various types of grogs indicates modes of production based on intensive recycling. The presence of some pottery vessels at the Estarrona site with chemical features similar to those of Peracho is indicative of the transport of pieces during the migrations of semi-sedentary groups and/or the exchange of pieces between different groups of humans.     

An interlaboratory comparison of energy dispersive X-ray microanalysis (EDX) of titanium and zirkonium nitrides

The results of an interlaboratory comparison of energy dispersive X-ray microanalysis of TiN_0.84 and ZrN were presented. The microprobe group of the German Physical Society (DPG) and the Federal Institute for Materials Research and Testing (BAM) had initiated the interlaboratory comparison. The primary aim was to test modern EDX systems equipped with ultrathin windows concerning the accuracy and reliability of the analysis of compounds containing light elements. The participants from 23 laboratories performed the analysis at different primary energies, in the standard-less mode as well as on the base of own standards, and considering Ti-K or Ti-L in case of TiN_0.84. The results show a slight overestimation of the nitrogen content and a large standard deviation from the mean value. Reasons for the scattering of the results are discussed.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Validation of scanning electron microscope (SEM), energy dispersive X-ray (EDX) and gamma spectrometry to verify source nuclear material for safeguards purposes

Ten ore samples, two unpurified yellow cake samples and natural uranyl nitrate hexahydrate sample were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) method to verify source nuclear material. Samples represent source nuclear material as possible. All samples were scanned at ideal conditions; working distance = 10 mm, voltage = 30 kV, magnification value = × 100, spot size = 50 to screen samples for the presence of uranium and thorium, Also Hyper pure germanium (HPGe) gamma spectrometers were applied to estimate the uranium and thorium contents in Bq/kg (ppm). For the ore samples uranium-238 ranges from 1,049.23 Bq/kg (85.30 ppm) to 2,096.06 Bq/kg (170.41 ppm), uranium-235 ranges from 47.51 to 105.61 Bq/kg and thorium-232 ranges from 22.84 Bq/kg (5.65 ppm) to 41.78 Bq/kg (10.34 ppm). For the yellow cake samples and uranyl nitrate hexahydrate uranium-238 ranges from 42.99 Bq/kg (3.50 ppm) to 71,887.2 Bq/kg (5,844.49 ppm) and thorium-232 is 4.78 Bq/kg (1.83 ppm) and the other two samples are lower than the detection limit.     

Chemical and morphological study of gunshot residue persisting on the shooter by means of scanning electron microscopy and energy dispersive X-ray spectrometry

Persistence of gunshot residue (GSR) simultaneously collected from hands, face and hair, and clothing of the shooting person was examined. Samples were collected from five shooters in nine time intervals after a single shoot with a Luger 9 mm pistol, in the range of 0-4 h and examined with scanning electron microscopy and energy dispersive X-ray spectrometry. Numbers of particles, frequencies of occurrence of certain compositions of particles, and their sizes in function of the time intervals were inspected. The greatest numbers of particles were observed in samples collected from hands right after shooting, but they decrease quickly with time. In samples collected from the face smaller initial numbers of particles were found, but they lasted at a similar level longer. The estimated half-life times of particles were less than 1 h for samples taken from the hands, over 1 h for clothing and about 2-3 h for the face. In samples collected at longer intervals after shooting, there were particles present of small sizes and irregular shapes. The results demonstrate that including evidence collected from the suspect's face and hair may increase the probability of detection of GSR in cases when the suspect has not been apprehended immediately after the investigated incident.     

Microstructural characterisation of five simulated archaeological copper alloys using light microscopy, scanning electron microscopy, energy dispersive X-ray microanalysis and secondary ion mass spectrometry

This paper describes the microstructural characterisation of five simulated archaeological copper alloys, produced by modern powder technology. The chemical composition of the examined bronzes covers the major families of archaeological bronzes from antiquity until the Roman period. Light microscopy (LM), energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM) as well as two- and three-dimensional secondary ion mass spectrometry (SIMS) have been used to describe the main properties of the alloys. The results show a heterogeneous microstructure on a micrometer scale, formed by metallic and non-metallic phases. The latter are conglomerates of oxides or sulphides of major or minor elements.     

Chemical characterization of particulate matter suspended in the atmosphere by energy dispersive X-ray fluorescence (EDXRF)

Summary This paper presents the first measurement of the elemental composition of the suspended particulate matter in the atmosphere of Londrina city (Paraná State, Brazil). The sampling was accomplished in the summer of 2003 and in the winter of 2002, with a stacker filter holder, collecting simultaneously the fine particulates (PM_2.5) and the coarse particulates (PM₁₀). The concentration of K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb associated with particulate matter was determined by energy dispersive X-ray fluorescence. The results of the grouping analysis suggested that the elements in the aerosol particles came from two sources: soil re-suspension and industrial or anthropogenic activities.     

Simultaneous determination of cobalt, copper and zinc by energy dispersive X-ray fluorescence spectrometry after preconcentration on PAR-loaded ion-exchange resin.

A sensitive method for the preconcentration and determination of trace amounts of Co, Cu and Zn by energy-dispersive X-ray fluorescence spectrometry (EDXRF) has been developed. The method is based on the fact that 4-(2-pyridylazo)-resorcinol (PAR) loaded Dowex anion-exchange resin (PAR-resin) can effectively adsorb Co, Cu and Zn at pH 9.0 to form PAR-metal complexes. The detection limits for Co, Cu and Zn were 1.53, 0.31 and 0.21 ppb, respectively. The precisions for five replicate measurements of the three metals were 3.4, 2.7 and 2.1% RSD, and the calibration curves were linear up to 75 microg with correlation coefficients of 0.9975, 0.9980 and 0.9985, respectively. The method was successfully applied for the simultaneous determination of Co, Cu and Zn in seawater samples at ppb levels.     

Probing stepwise reaction of NNP-ligand copper(I) complex with elemental sulfur by using N-heterocyclic carbene as a trapper

The dinuclear NNP-ligand copper(I) complex [o-N═CH(C(4)H(3)N)-PPh(2)C(6)H(4)](2)Cu(2) (1) has been synthesized by the reaction of (CuMes)(4) (Mes = 2,4,6-Me(3)C(6)H(2)) with N-((1H-pyrrol-2-yl)-methylene)-2-(diphenylphosphino)benzenamine under an elimination of MesH. Further reaction of 1 with an excess of S(8) produced a mononuclear Cu(II) complex [o-N═CH(C(4)H(3)N)-P(S)Ph(2)C(6)H(4)](2)Cu (5) and CuS. CuS was identified by Raman spectroscopy and 1 and 5 were clearly confirmed by X-ray crystallography. The N-heterocyclic carbene was employed to react with 1 to give a mononuclear [o-N═CH(C(4)H(3)N)-PPh(2)C(6)H(4)]Cu{C[N(iPr)CMe](2)} (2). The reactions of 2 were carried out with (1)/(8), (2)/(8), and (5)/(8) equiv of S(8), leading to compounds [o-N═CH(C(4)H(3)N)-P(S)Ph(2)C(6)H(4)]Cu{C[N(iPr)CMe](2)} (3), [o-N═CH(C(4)H(3)N)-P(S)Ph(2)C(6)H(4)]Cu (4), and 5 respectively, in which CuS was generated in the third reaction and S═C[N(iPr)CMe](2) in the latter two reactions. The clean confirmation of 2-4 demonstrates a stepwise reaction process of 1 with S(8) to 5 and CuS and the N-heterocyclic carbene acts well as a trapping agent.     

Determination of copper,iron, nickel and zinc in ethanol fuel by energy dispersive X-ray fluorescence after pre-concentration on chromatography paper

This paper presents an alternative analytical method employing energy dispersive X-ray fluorescence (EDXRF) to determine copper, iron, nickel and zinc ions in ethanol fuel samples after a pre-concentration procedure. Our pre-concentration strategy utilizes analyte retention on cation exchange chromatography paper, a convenient substrate for direct EDXRF measurements. The repeatability, expressed in terms of RSD of standard solutions containing 0.25 μg mL⁻¹ of Cu, Fe, Ni and Zn, and calculated from fifteen consecutive measurements, was 2.5, 2.8, 3.0, and 2.7%, respectively. The limits of detection (LOD), defined as the analyte concentration that gives a response equivalent to three times the standard deviation of the blank (n = 10), were found to be 13, 15, 15 and 12 μg L⁻¹ for Cu, Fe, Ni and Zn, respectively. The proposed method was applied to Cu, Fe, Ni and Zn determination in hydrated ethanol fuel samples collected from different gas stations.     

Structural characterization of ultrasmall superparamagnetic iron oxide (USPIO) particles in aqueous suspension by energy dispersive X-ray diffraction (EDXD)

Ultrasmall superparamagnetic iron oxide (USPIO) particles were structurally characterized in situ in an aqueous dilute suspension by energy dispersive X-ray diffraction (EDXD) and ex situ as powders obtained by lyophilization of the suspension by angular dispersive X-ray diffraction (ADXD) at 20 degrees C. Structural parameters obtained by the Rietveld method on ADXD data were used as starting parameters for modeling the structure of the particles in suspension. Although each particle is a single crystal, as evidenced by conventional X-ray diffraction, our results indicate that the structural order, specific to a crystal, does not extend to the entire volume of the particle. In fact, each individual particle, averagely, has a crystalline structural extension ca. 4.0 nm smaller than the apparent dimensions obtained by both ADXD and TEM (ca. 8.0 nm).     

Characterization of particulate matter from the Metropolitan Zone of the Valley of Mexico by scanning electron microscopy and energy dispersive X-ray analysis

Samples of total suspended particles (TSP) and PM10 respirable particles from five monitoring stations from the network system of the Metropolitan Zone of the Valley of Mexico (MZVM) were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). Morphology and chemical composition allowed to identify six groups. The analysis shows that the most abundant groups are Al-Si-O, Fe, and metals, the first one in the TSP fraction. Trace metal, commonly associated to PM10 at a receptor location, will depend on the relative influences of local anthropogenic sources. Metal group was observed in all samples, mainly in Tlalnepantla and CES zones (28–46%).     

Trace elements determination by energy dispersive X-ray fluorescence (EDXRF) in human placenta and membrane: a comparative study

This work is an application of energy dispersive X-ray fluorescence (EDXRF) as an analytical technique for trace elemental determination in human membrane and placenta and elemental concentrations correlations in both tissues. Whole samples were collected during the delivery from healthy mothers and full-term pregnancies. The age of the mother was between 25 and 40 years old, and the weight of the infants ranged from 2.56 to 4.05 kg. Samples were lyophilised and analysed without any chemical treatment. No significant differences in elemental content of placenta and membrane samples were observed except for Ca. Very low levels of Se, As and Pb were observed in all the analysed samples. Zn, considered as one of the key elements in newborn health, was not significantly different in the analysed samples, all of which originated from healthy mothers and healthy babies. The obtained values agree with the literature except for Ca, which is much higher in the studied samples.     

Determination of lanthanides by source excited energy dispersive X-ray fluorescence (EDXRF) method after preconcentration with ammonium pyrrolidine dithiocarbamate (APDC)

A new analytical procedure for determination of lanthanides in environmental samples after chemical separation from major matrix elements on DOWEX 50W-X8 resin followed by preconcentration with chelating agent ammonium pyrrolidine dithiocarbamate (APDC) and analyses of thin targets by energy dispersive X-ray fluorescence (EDXRF) method using ¹⁰⁹Cd as the source of excitation was presented. Characteristic L X-ray lines of the lanthanides were used for calculations of the net peak area and mass concentrations. The influence of pH value of the solution and addition of organic matter on the complexation was investigated. Percentage of recovery of each lanthanide after separation on DOWEX 50W-X8 resin was also determined. Accuracy of the method was tested on standard reference materials and real environmental samples (red mud material). For that purpose samples of standard reference materials and red mud were prepared as thick targets and directly analyzed (without the separation step) by EDXRF method using ²⁴¹Am as the excitation source. In that case lanthanides concentrations were determined over their characteristic K X-ray lines and results were compared with those obtained after separation/preconcentration step described above. Results showed that selected lanthanides made stable complexes with APDC in the alkaline medium with the maximum recovery at pH = 8. The presence of organic matter slightly modified the complexation by means of somewhat higher recovery percentage at pH lower than 7 and approx. 20% lower recovery at pH higher than 7.

Recovery of the elements after separation on DOWEX 50W-X8 resin and preconcentration with APDC at pH = 8 varied from 91.4% (Pr) to only 24.9% in the case of Dy.

Concentrations of lanthanides measured in standard reference material and environmental samples of red mud after microwave digestion, separation on DOWEX 50W-X8 resin, preconcentration with APDC at pH = 8 and recalculation on the percentage of recovery were in good agreement with certified values in the case of SRM as well as with the concentrations obtained by direct determination over K lines using ²⁴¹Am excitation source in the case of red mud leading to the conclusion that presented method was applicable for the determination of lanthanides in real environmental samples.     

Information-theoretical feature selection using data obtained by scanning electron microscopy coupled with and energy dispersive X-ray spectrometer for the classification of glass traces

In this work, a selection of the best features for multivariate forensic glass classification using Scanning Electron Microscopy coupled with an Energy Dispersive X-ray spectrometer (SEM-EDX) has been performed. This has been motivated by the fact that the databases available for forensic glass classification are sparse nowadays, and the acquisition of SEM-EDX data is both costly and time-consuming for forensic laboratories. The database used for this work consists of 278 glass objects for which 7 variables, based on their elemental compositions obtained with SEM-EDX, are available. Two categories are considered for the classification task, namely containers and car/building windows, both of them typical in forensic casework. A multivariate model is proposed for the computation of the likelihood ratios. The feature selection process is carried out by means of an exhaustive search, with an Empirical Cross-Entropy (ECE) objective function. The ECE metric takes into account not only the discriminating power of the model in use, but also its calibration, which indicates whether or not the likelihood ratios are interpretable in a probabilistic way. Thus, the proposed model is applied to all the 63 possible univariate, bivariate and trivariate combinations taken from the 7 variables in the database, and its performance is ranked by its ECE. Results show remarkable accuracy of the best variables selected following the proposed procedure for the task of classifying glass fragments into windows (from cars or buildings) or containers, obtaining high (almost perfect) discriminating power and good calibration. This allows the proposed models to be used in casework. We also present an in-depth analysis which reveals the benefits of the proposed ECE metric as an assessment tool for classification models based on likelihood ratios.     

Decomposition of nitrogen and dinitrogen oxides on copper and copper(I) oxide in elemental analysis by reaction gas chromatography

The decomposition of NO and N₂O on Cu and Cu₂O packings was studied in view of the simultaneous determination of N and S in organic compounds by the Pregl-Dumas method in a system of reaction gas chromatography, and the mass balance of the reactions taking place was carried out. The amounts of NO and N₂O that are decomposed on the reduction packing at temperatures within 883 and 1263 °K are quoted. The reduction activity of both packings toward NO decreases with increasing temperature, while both the reduction and sorption activity of Cu₂O is markedly lower than that of the Cu one. No significant sorption of NO was observed at temperatures within 883 and 923 °K and no sorption of gaseous N₂ and N₂O occurred on either packing.