Direct and simultaneous determination of copper, chromium, aluminum, and manganese in urine with a multielement graphite furnace atomic absorption spectrometer

A simple method was developed for the direct and simultaneous determination of copper, chromium, aluminum, and manganese in urine using a multielement GFAAS (Perkin-Elmer SIMAA6000). Pd was used as the chemical modifier along with a special purge gas (5% H2 in Ar). A simple calibration curve method can be used (with 1:1 dilution). A standard reference material (Seronorm Trace Elements Urine) was used to find the optimal temperature program and to confirm the accuracy of the technique. The analyzed values were within 90-110% of the certified values. The relative standard deviations were 1.7, 1.5, 1.6, and 1.5% for these four elements and the detection limits were 0.08 microg L(-1) for Cu, 0.05 microg L(-1) for Cr, 0.06 microg L(-1) for Al, and 0.06 microg L(-1) for Mn. The recoveries of Cu, Cr, Al, and Mn from real urine samples were 100 +/- 5%, except for Cu (80%). The found values of Cu, Cr, Al, and Mn in a real urine sample were 14.3, 0.78, 18.9, and 0.06 microg L(-1), respectively. Scanning electron micrographs were used to investigate the physical form of Pd on the surface of the platform in the graphite furnace. Use of 5% H2 in Ar as the purge gas resulted in smaller and more uniformly distributed Pd particles (Pd particle diameters 0.4-0.6 microm using 5% H2 in Ar compared to 0.4-1.2 microm using pure Ar), increasing the effect of the Pd chemical modifier and promoting the efficiency of atomization.     

Absence of exchange interaction between localized magnetic moments and conduction-electrons in magnetic ions diluted in Ag-nanoparticles

The Electron Spin Resonance (ESR) of diluted magnetic ions (MI) of Er3+, Yb3+ and Mn2+ in Ag nanoparticles (NPs) is reported. Monodisperse samples of Ag NPs doped with these MI were synthesized by reducing silver nitrate and MI-oxides. This simple method can be extended to all rare-earths. The measurements of the g-values and hyperfine splittings indicates that the MI are located at cubic sites in the Ag:MI NPs. The ESR spectra show that there is no g-shift and Korringa-relaxation due to the exchange interaction between the MI and the conduction electrons, suggesting that the exchange interaction is absent in the Ag:MI NPs. Thus, the nature of this interaction needs to be reexamined at the nanoscale range.     

Quantification of four major metabolites of embryotoxic N-methyl- and N-ethyl-2-pyrrolidone in human urine by cooled-injection gas chromatography and isotope dilution mass spectrometry

N-Methyl- and N-ethyl-2-pyrollidone (NMP and NEP) are frequently used industrial solvents and were shown to be embryotoxic in animal experiments. We developed a sensitive, specific, and robust analytical method based on cooled-injection (CIS) gas chromatography and isotope dilution mass spectrometry to analyze 5-hydroxy-N-ethyl-2-pyrrolidone (5-HNEP) and 2-hydroxy-N-ethylsuccinimide (2-HESI), two newly identified presumed metabolites of NEP, and their corresponding methyl counterparts (5-HNMP, 2-HMSI) in human urine. The urine was spiked with deuterium-labeled analogues of these metabolites. The analytes were separated from urinary matrix by solid-phase extraction and silylated prior to quantification. Validation of this method was carried out by using both, spiked pooled urine samples and urine samples from 56 individuals of the general population with no known occupational exposure to NMP and NEP. Interday and intraday imprecision was better than 8% for all metabolites, while the limits of detection were between 5 and 20 μg/L depending on the analyte. The high sensitivity of the method enables us to quantify NMP and NEP metabolites at current environmental exposures by human biomonitoring.     

Cr替代Mn对La0.4Ca0.6MnO3磁性质的影响

用固相反应法制备了La0.4Ca0.6Mn1-xCrxO3(x=0.00,0.02,0.04,0.06,0.08,0.10,0.15)多晶样品,通过X射线衍射(XRD)图谱、磁化强度-温度(M-T)曲线、电子自旋共振(ESR)谱线,研究了Cr替代Mn对La0.4Ca0.6MnO3磁性质的影响.实验结果表明:La0.4Ca0.6MnO3存在复杂的磁结构,在258 K出现电荷有序相,从175 K到50 K,产生强关联CO-AFM(电荷有序?反铁磁)相,温度降到41 K左右出现自旋玻璃态;当替代量x≥0.06时,电荷有序相被融化;当x≥0.10时,自旋玻璃态被融化.对实验结果进行了初步解释:电荷有序相被融化主要原因是Cr3+与Mn4+具有相同的电子结构,Cr3+替代Mn3+破坏了CE型反铁磁的自旋序,从而引起电荷序的坍塌,实验证明了电荷序CE型反铁磁体系中,电荷序和自旋序之间存在强耦合相互作用;自旋玻璃态的融化,是由于Cr替代Mn破坏了自旋玻璃态的生成条件,即反铁磁背景下有少量铁磁成分.     

Speciation of methylcyclopentadienyl manganese tricarbonyl by high-performance liquid chromatography-diode laser atomic absorption spectrometry

Methylcyclopentadienyl manganese tricarbonyl (MMT) is a fuel additive that has been marketed for use in unleaded gasoline since December 1995. The widespread use of this additive has been suggested to cause health risks, but limitations in data regarding its degradation products and their toxicity prevent an accurate evaluation. To monitor the organomanganese compounds, it is clearly advantageous to employ low-cost, high-sensitivity, manganese-specific instrumentation to perform speciation. In this work, instrumentation fitting these criteria was obtained by the combination of high-performance liquid chromatography (HPLC) with diode laser atomic absorption spectrometry (DLAAS) and was used to determine MMT, its nonmethylated derivative, cyclopentadienyl manganese tricarbonyl (CMT), and inorganic manganese. DLAAS was shown to be a versatile analytical technique for total Mn determination, with a detection limit of 1 ng/mL and a linear dynamic range (LDR) of almost 5 orders of magnitude. Analytical figures of merit for HPLC-DLAAS included a detection limit of 2 ng(as Mn)/mL, a LDR of 3 orders of magnitude, and an analysis time of three minutes. The organometallic compounds are characterized by rapid photolysis in sunlight, and hence, experiments were performed to evaluate whether normal laboratory lighting is suitable for their determination. Our results showed that normal laboratory protocols may be employed except that the organomanganese compounds should be stored away from light except during sample introduction procedures. The ability of the instrumentation to selectively preconcentrate organomanganese compounds while removing inorganic manganese was demonstrated. Sufficient resolution was obtained to determine a 20-fold excess of CMT compared with MMT. The ability of the system to do practical analysis was demonstrated by the accurate determination of MMT in spiked samples of gasoline, human urine, and tap water. These results demonstrate the suitability of HPLC-DLAAS for the speciation of MMT and its derivatives in industrial, toxicological, and environmental samples.     

Determination of optical coefficients and fractal dimensional parameters of cancerous and normal prostate tissues

Optical extinction and diffuse reflection spectra of cancerous and normal prostate tissues in the 750 to 860 nm spectral range were measured. Optical extinction measurements using thin ex vivo prostate tissue samples were used to determine the scattering coefficient (μ(s)), while diffuse reflection measurements using thick prostate tissue samples were used to extract the absorption coefficient (μ(a)) and the reduced scattering coefficient (μ'(s)). The anisotropy factor (g) was obtained using the extracted values of μ(s) and μ'(s). The values of fractal dimension (D(f)) of cancerous and normal prostate tissues were obtained by fitting to the wavelength dependence of μ'(s). The number of scattering particles contributing to μ(s) as a function of particle size and the cutoff diameter d(max) as a function of g were investigated using the fractal soft tissue model and Mie theory. Results show that d(max) of the normal tissue is larger than that of the cancerous tissue. The cutoff diameter d(max) is observed to agree with the nuclear size for the normal tissues and the nucleolar size for the cancerous tissues. Transmission spectral polarization imaging measurements were performed that could distinguish the cancerous prostate tissue samples from the normal tissue samples based on the differences between their absorption and scattering parameters.     

Luminescence properties of nano-sized Sr2MgSiO5: Eu2+, Mn2+ phosphors prepared by the sol-gel method

Nano-sized Sr2MgSiO5:Eu2+, Mn2+ phosphor was synthesized by the sol-gel method. The preparation conditions of the precursor were determined. The effect of Eu2+ and Mn2+ content on the luminescence intensity was studied. X-ray diffraction (XRD), photoluminescence spectra (PL), and photoluminescence excitation spectra (PLE) were used to characterize the samples. The results showed that the excitation bands ranged from 250 to 450 nm, and their peaks positioned around 365 nm. The emission spectrum consists of three bands: blue, green, and red, respectively. The blue and green emission bands originate from the center of the Eu2+, while the red emission band is attributed to the energy transfer from Eu2+ to Mn2+. White light can be obtained by mixing the three emission colors. The experiment results show that the Sr2MgSiO5:Eu2+, Mn2+ is a single host phosphor with superior properties for use in white light emitting diodes (white LED).     

Effect of Mn precursors on benzene oxidation with ozone over MnOx/MCM-41 at low temperature

Low temperature benzene oxidation in the presence of ozone on MnOx/MCM-41 catalysts has been studied. MnOx/MCM-41 catalysts were prepared from two different precursors, Mn(NO3)2 and Mn(CH3COO)2, and these samples were characterized by N2 sorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction. The characterization results showed that the MnOx/MCM-41 prepared from Mn(CH3COO)2 had higher oxygen mobility and dispersion than the MnOx/MCM-41 from Mn(NO3)2. As a result, the MnOx/MCM-41 obtained from Mn(CH3COO)2 showed higher catalytic activity for the oxidation of benzene using ozone; however, without ozone, the catalytic activity was negligible.     

Real structure of TiO2 in samples of the TiO2-V2O5 system

Measurements of electron spin resonance (ESR) spectra and X-ray structure analysis have been performed on samples of the TiO₂-V₂O₅ system, formed by anatase crystallites on the surface of which a thin layer of V₂O₅ was deposited by thermal decomposition of ammonium vanadate at 800°C. It was found that the deposited V₂O₅ gives rise to a change in the modification of TiO₂ (anatase goes over to rutile) and to a decrease in the volume of the TiO₂ elementary cell. Bands corresponding to Ti atoms of oxidation state +III were identified in the ESR spectrum of the initial TiO₂. The intensity of these bands decreases with increasing content of V₂O₅ in the TiO₂-V₂O₅ samples; the ESR spectra of the samples with high V₂O₅ content exhibit only one band corresponding to vanadium atoms in oxidation state +IV in the rutile lattice. The experimental results allow one to form an idea on the changes of the real structure of TiO₂ in connection with the deposition of V₂O₅ thin films on TiO₂ crystallites and with thermal treatment of these materials.     

Determination of lead in blood and urine by SPME/GC.

Lead is the most frequently quantitated toxic metal in biological matrixes. In this paper, a method is described for lead determination in whole blood and urine using solid-phase microextraction (SPME) gas chromatography. Lead ion is first derivatized with sodium tetraethylborate to form tetraethyllead, which is then extracted from the headspace over the sample by SPME. The analytical procedure was optimized for coating selection, pH, extraction time, and effect of salt. The relative standard deviation was less then 10% for both urine and blood samples. The limit of detection was 3 and 4 ppb; the limit of quantification is 5 and 10 ppb for urine and blood samples, respectively. Good linearity was found for both urine and blood samples when PDMS coating was used. The standard addition method was used for quantitation. Certified urine and blood samples were analyzed, and good accuracy was obtained.     

纳米V2O5的晶体缺陷与导电性能研究

用溶胶－凝胶法制备纳米Ｖ２Ｏ５粉体，利用ＩＲ、ＥＳＲ结构分析手段研究晶体缺陷，并用阻抗谱研究它的导电性能。阻抗谱表明，在较低退上得到的纳米Ｖ２Ｏ５粉体（平均粒径为５．０ｎｍ）表现出超常的导电性能，其电导率高于其它样品二个数量级。ＩＲ、ＥＳＲ分析指出，该样品中Ｖ２Ｏ５结构发生严重畸变，引起氧空位浓度增加，并认为是导致良好导电性能之主要原因。     

Investigations of the electrical property, diffuse reflectance and ESR spectra of the La-(Fe,Mn)-codoped PTCR BaTiO3 annealed in reducing atmosphere

Electrical properties of La-(Fe,Mn)-codoped positive temperature coefficient of resistivity (PTCR) BaTiO₃ ceramics were studied by combining their diffuse reflectance measurements and electron spin resonance (ESR) spectroscopy. La-(Fe,Mn)-codoped samples showed high durability to reducing atmosphere. It is assumed that Fe and Mn ions segregated in the grain boundary contribute to the density of surface acceptor states, meanwhile localizing electrons in a form of Ti³⁺ and stabilizing the chemisorbed oxygens through La³⁺-Mn^3+,4+ or La³⁺-Fe³⁺ pairs. In addition, ESR signals of Fe³⁺ in annealed samples was intensified above Curie temperature (T_c), indicating that Fe ions still maintained its high valence states (Fe³⁺) in the grain boundary even after annealing in reducing atmosphere.     

Urinary globotriaosylsphingosine-related biomarkers for Fabry disease targeted by metabolomics

Fabry disease is a lysosomal storage disorder caused by deficiency of α-galactosidase A, resulting in glycosphingolipid accumulation in organs and tissues, including plasma and urine. Two disease-specific Fabry biomarkers have been identified and quantified in plasma and urine: globotriaosylceramide (Gb(3)) and globotriaosylsphingosine (lyso-Gb(3)). The search continues for biomarkers that might be reliable indicators of disease severity and response to treatment. The main objective of this study was to target other urinary biomarkers using a time-of-flight mass spectrometry metabolomic approach. Urinary metabolites of 63 untreated Fabry patients and 59 controls were analyzed. A multivariate statistical analysis performed on a subset of male samples revealed seven novel Fabry biomarkers in urine, all lyso-Gb(3) analogues having modified sphingosine moieties. The empirical formulas of the sphingosine modifications were determined by exact mass measurements (- C(2)H(4), - C(2)H(4) + O, - H(2), - H(2) + O, + O, + H(2)O(2), + H(2)O(3)). We evaluated the relative concentration of lyso-Gb(3) and its seven analogues by measuring area counts for each analogue in all Fabry patients. All samples were normalized to creatinine. We found higher concentrations for males with Fabry disease compared to females. None of these biomarkers were detected in controls. To our knowledge, this is the first time that lyso-Gb(3)-related Fabry disease biomarkers are detected in urine.     

Separation of no-carrier-added 52Mn from bulk chromium: a simulation study for accelerator mass spectrometry measurement of 53Mn

53Mn radionuclide (T(1/2) = 3.7 x 10(6) y) is produced through the interaction of cosmic rays. Measurements of concentrations of 53Mn in rocks might help to understand Earth surface processes that occurred in time periods not accessible with other cosmogenic nuclides. Only accelerator mass spectrometry (AMS) can determine such ultratrace levels of 53Mn. The main interference in the detection of 53Mn by AMS is its stable isobar 53Cr, which is roughly approximately 10(12) times more abundant in nature. A prerequisite of any AMS measurement of 53Mn in geological samples is therefore chromium separation by an efficient chemistry. Thus, we have developed a method for the separation of chromium and manganese by using a radiometric simulation. The separation procedure was monitored by 51Cr (T(1/2) = 27.70 d) and 52Mn (T(1/2) = 5.59 d) as the corresponding radiotracers for chromium and manganese, respectively. The separation studies were performed by a liquid-liquid extraction technique using trioctylamine (TOA) diluted in cyclohexane. A high separation factor (approximately 16 000) for Mn and Cr can be obtained at optimal conditions of 0.8 M TOA and 9 M HCl. The developed method has been found equally applicable for real geological samples such as manganese crusts, lava, and sediment samples. Therefore, the method offers an important tool to improve 53Mn measurements by AMS.     

Multivariate analysis of selected metals in tannery effluents and related soil

Effluent and relevant soil samples from 38 tanning units housed in Kasur, Pakistan, were obtained for metal analysis by flame atomic absorption spectrophotometric method. The levels of 12 metals, Na, Ca, K, Mg, Fe, Mn, Cr, Co, Cd, Ni, Pb and Zn were determined in the two media. The data were evaluated towards metal distribution and metal-to-metal correlations. The study evidenced enhanced levels of Cr (391, 16.7 mg/L) and Na (25,519, 9369 mg/L) in tannery effluents and relevant soil samples, respectively. The effluent versus soil trace metal content relationship confirmed that the effluent Cr was strongly correlated with soil Cr. For metal source identification the techniques of principal component analysis, and cluster analysis were applied. The principal component analysis yielded two factors for effluents: factor 1 (49.6% variance) showed significant loading for Ca, Fe, Mn, Cr, Cd, Ni, Pb and Zn, referring to a tanning related source for these metals, and factor 2 (12.6% variance) with higher loadings of Na, K, Mg and Co, was associated with the processes during the skin/hide treatment. Similarly, two factors with a cumulative variance of 34.8% were obtained for soil samples: factor 1 manifested the contribution from Mg, Mn, Co, Cd, Ni and Pb, which though soil-based is basically effluent-derived, while factor 2 was found associated with Na, K, Ca, Cr and Zn which referred to a tannery-based source. The dendograms obtained from cluster analysis, also support the observed results. The study exhibits a gross pollution of soils with Cr at levels far exceeding the stipulated safe limit laid down for tannery effluents.     

Effects of cryogenic grinding on soft-tissue optical properties

Optical properties obtained from spectrophotometer measurements of reflectance and transmittance were determined for both frozen-ground and intact soft tissues. The tissues used in these experiments were calf aorta, rat jejunum, and rabbit sciatic nerve. Tissue specimens from each tissue type were frozen in liquid nitrogen and then ground with a pestle and mortar into a fine powder. A tissue paste formed once the powder returned to room temperature. The tissue paste was then sandwiched between glass slides for spectrophotometer measurements. For comparison, the optical properties of the intact specimens were also measured. Total transmission and diffuse reflection were obtained on a Varian Cary 5E spectrophotometer (400-850 nm). Absorption and reduced scattering coefficients of the tissues were determined with the Inverse Adding Doubling method. Our results suggested that within the 400-nm to 850-nm spectrum, optical properties of the ground tissue approximated intact tissue within limits of experimental error.     

溶胶-凝胶法和微波辐射法制备Mg2SiO4Mn2＋红色荧光粉制备及发光性质的研究

采用溶胶-凝胶法和微波辐射法制备了Mg2SiO4Mn2＋红色发光材料。研究了以Mg2SiO4为基质,在掺杂Mn2＋的情况下,微波合成时间和Mn2＋的掺杂浓度对发光性能的影响。选择最佳微波合成时间和Mn2＋的掺杂浓度,制备了在410nm激发下,发光中心位于690nm的红色发光材料。     

Effects of Cr,Mn, Si,Cu and Zr on microstructure and mechanical properties of high carbon Fe–16Al alloy

Abstract

Effects of alloying elements Cr, Mn, Si, Cu and Zr on the microstructure and mechanical properties of Fe₃Al (Fe–16Al) based alloy containing ～0·5 wt-%C have been investigated. Six alloys were prepared by a combination of air induction melting with flux cover and electroslag refining (ESR). ESR ingots were hot forged and hot rolled at 1373 K and were further characterised with respect to microstructure and mechanical properties. The base alloy and the alloys containing Cr, Mn, Si and Cu exhibit a two phase microstructure of Fe₃AlC_0·5 precipitates in Fe₃Al matrix whereas the alloy containing Zr exhibits a three phase microstructure, the additional phase being Zr rich carbide precipitates. Cr and Mn have high solubility in Fe₃AlC_0·5 precipitates as compared to Fe₃Al matrix whereas Cu and Si have very high solubility in Fe₃Al matrix compared to Fe₃AlC_0·5 precipitate and Zr has very low solubility in both Fe₃Al matrix and Fe₃AlC_0·5 precipitate. No significant improvement in room and high temperature (at 873 K) strengths was observed by addition of these alloying elements. Furthermore, it was observed that addition of these alloying elements has resulted in poor room and high temperature ductility. Addition of Cr, Mn, Si and Cu has resulted in marginal improvement in creep life, whereas Zr improved the creep life significantly from 22·3 to 117 h.     

Transmission- and side-detection configurations in ultrasound-modulated optical tomography of thick biological tissues

Ultrasound-modulated optical tomography of thick biological tissues was studied based on speckle-contrast detection. Speckle decorrelation was investigated with biological tissue samples of various thicknesses. Images of optically absorbing objects buried in biological tissue samples with thicknesses up to 50 mm were obtained in a transmission-detection configuration. The image contrast was more than 30%, and the spatial resolution was approximately 2 mm. In addition, a side-detection scheme along with two specific configurations were examined, and the advantages were demonstrated. Experimental results implied feasibility of applying the ultrasound-modulation technique to characterize optical properties in inhomogeneous biological tissues.     

Monitoring polycyclic aromatic hydrocarbon metabolites in human urine: extraction and purification with a sol-gel glass immunosorbent.

A new, rapid method for selective extraction of hydroxylated polycyclic aromatic hydrocarbons metabolites (OH-PAHs) in human urine was developed using an immunosorbent of anti-pyrene antibodies which were encapsulated in a sol-gel glass (SGG) matrix. Resulting chromatograms after immunoextraction of urine samples and HPLC analysis of the extracts were free from matrix interferences. The LODs for the determination of OH-PAHs in these difficult samples were in the low-ppt range (1-16 ng/L). In addition to its high selectivity, the immunosorbent proved to be robust and reusable. Obtained recoveries in spiked urine samples ranged from 83 to 107% for the hydroxyphenanthrene and hydroxypyrene compounds under investigation, while recovery for 3-hydroxybenzo[a]pyrene was only 45-62%. In a biomonitoring study, the SGG immunosorbent was successfully used for trace-level analysis of OH-PAHs in 20 human urine samples. Results were compared to data obtained by an independent reference analysis method and revealed good correlation between both methods.