Etude Des Teneurs En Cuivre,Zinc, Et Arsenic Dans La Poudre De Lait Par Activation Neutronique

Abstract

Copper, zinc and arsenic have been determined in dehydrated milk powder by neutron activation analysis. Irradiation 13 of ashed milk powder in a flux of 10¹³ thermal neutrons per second per sq. cm. was followed by: elution through an anion exchange resin; solvent extraction of copper with dithizone into a chloroform phase; precipitation and subsequent redissolution of arsenic as As₂, S₃ and as a polysulfide, respectively. The determinative step involved gamma ray spectroscopy of the isotopes Zn⁶⁷, Zn⁶⁵, Cu⁶⁴ and As⁷⁶.     

用中子活化分析法研究25种元素在人体肝脏亚细胞组分中的分布

采用差速离心分离技术与中子活化分析法（ＮＡＡ）相结合的方法分析了人肝２５５中元素,并用标准参考物保证结果的准确性。分析结果表明,大多数元素在各亚细胞组分中并非均匀分布。Ａｓ、Ａｕ、Ｃｏ、Ｉ、Ｍｇ、Ｓｂ、Ｓｅ在细胞核和线粒体浓度最高。Ａｌ、Ｓｓ、Ａｕ、Ｂａ、Ｆｅ、Ｉ、Ｍｇ、Ｍｏ、Ｓｂ、Ｓｃ在细胞核和线粒体浓度最高。Ａｌ、Ａｓ、Ａｕ、Ｂａ、Ｆｅ、Ｉ、Ｌａ、Ｍｇ、Ｍｎ、Ｓｂ、Ｓｅ在胞液中深度最低,生物体     

Determination of Arsenic and Mercury in Various Environmental Matrices by Chemical Neutron Activation Analysis

Chemical neutron activation analysis was developed for determining trace amounts of arsenic and mercury in a variety of environmental matrices, including water, sediment, rock, plants, animal organs, etc: The adsorption procedure via magnesium oxide as the agent was applied to preconcentrate arsenic from the digested environmental matrices where arsenic in the form of As(V) ion could be highly efficiently adsorbed by hydrous magnesium oxide. On the other hand, the extraction procedure via lead diethyldithiocarbamate as the agent was applied to preconcentrate mercury from the digested environmental matrices where mercury in the form of Hg(II) ion could be highly efficiently extracted into the solution of lead diethyldithiocarbamte in dichloromethane. Both of the preconcentrated materials prepared ultimately in the solid states, i.e., arsenic in magnesium oxide and mercury in lead diethyldithiocarbamte were taken to be neutron irradiated. The γ spectra of the preconcentrated samples irradiated generally showed clear peaks of the product radionuclides from arsenic or from mercury by the different separation procedures. The possible interfering elements such as Na, Br, etc., were prominently minimized in respect of most of the preconcentrated samples. The reliability and accuracy of the proposed analytical methods for detecting arsenic and mercury can be confirmed by the assay of commercial standard reference materials including sediment, rock, plants, and animal organs.     

人肝细胞中砷代谢产物分析表征研究

采用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术对染砷后Chang肝细胞中的砷代谢产物进行分析.通过参考文献及相关实验推测出两种未知砷代谢产物,并采用标准合成加入法证明其中一种未知砷代谢产物为一甲基亚胂酸(MMAⅢ).定量分析结果显示,随着染砷浓度的增大,细胞中的-甲基砷、二甲基砷以及无机砷含量...     

Ethanol as a Solvent in the Determination of Arsenic in Marine Extracts by Atomic Absorption Spectrophotometry

Abstract

Arsenic is determined in aqueous solutions produced from marine raw materials by atomic absorption spectrophotometry. Conversion of the aqueous extract to an ethanol-extract increases the sensitivity of determination by a factor of 4 to 5. The method is applied to some selected samples produced from marine raw materials.     

Analysis and Speciation of Traces of Arsenic in Environmental,Food and Industrial Samples by Voltammetry: a Review

Voltammetric approaches for the determination of arsenic and speciation at trace levels are critically appraised in a review covering the literature from 1970 to 2002. Special attention is devoted to stripping modes and to issues related to the choice of working material and supporting electrolyte. A section is dedicated to the management of real samples and aspects of sample preparation. An extensive compilation, organized by real sample type, gathers essential experimental conditions. Potentiometric stripping analysis is introduced for sake of comparison. The coupling of voltammetric detection or preaccumulation with FIA, chromatography, capillary electrophoresis and ICP techniques is also addressed.     

我国成年人甲状腺碘含量的检测--微堆超热中子活化法测碘

采用微堆仪器超热中子活化分析法,测定了我国南北地区７８例正常年人甲状腺碘的含量,发现存在地区性差异,从而为评价碘对人体健康的影响提供了背景资料。     

Simple Method for Simultaneous Determination of Selenium and Arsenic in Human Hair by Means of Atomic Fluorescence Spectrometry with Hydride Generation Technique

This study describes a simple, rapid and reliable method for simultaneous determination of selenium and arsenic in human hair by means of atomic fluorescence spectrometry combined with a hydride generation technique (HG-AFS). The procedure developed encompasses microwave digestion of a sample in the nitric acid environment only. The interferences caused by nitrous oxides are eliminated by removing a gas from above the digested solution with a stream of argon. The sample is then chemically treated in a flow-through hydride generation system and exposed to measurements in a double-channel atomic fluorescence spectrometer. The method permits determining both analytes in the linear range of 0.5–100µgL^–1 with a detection limit equal to 0.2µgL^–1, as well as with very good repeatability not exceeding 1% for Se and 2% for As. No mutual interferences from either of the analytes in the concentrations ranges matching the hair composition were found. The method was verified in terms of accuracy with the use of a reference material and then applied to the analysis of the natural samples of human hair.     

Characterization and determination of 28 elements in fly ashes collected in a thermal power plant in Argentina using different instrumental techniques

Different techniques were selected for comprehensive characterization of seven samples of fly ashes collected from the electrostatic precipitator of the San Nicolás thermal power plant (Buenos Aires, Argentina). Particle size was measured using laser based particle size analyzer. X-ray diffraction powder (XRD) analysis and scanning electron microscopy (SEM) were used to characterize the mineral phase present in the matrix consisting basically of aluminosilicates and large amounts of amorphous material. The predominant crystalline phases were mullite and quartz. Major and minors elements (Al, Ca, Cl, Fe, K, Mg, Na, S, Si and Ti) were detected by energy dispersive X-ray analysis (EDAX). Trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, V and Zn) content was quantified by inductively coupled plasma optical emission spectrometry (ICP OES). Different acid mixtures and digestion procedures were compared for subsequent ICP OES measurements of the dissolved samples. The digestion procedures used were: i) a mixture of FH + HNO₃ + HClO₄ (open system digestion); ii) a mixture of FH + HNO₃ (MW-assisted digestion); iii) a mixture of HF and aqua regia (MW-assisted digestion). Instrumental neutron activation analysis (INAA) was employed for the determination of As, Ba, Co, Cr, Ce, Cs, Eu, Fe, Gd, Hf, La, Lu, Rb, Sb, Sc, Sm, Ta, Tb, Th, U and Yb. The validation of the procedure was performed by the analysis of two certified materials namely, i) NIST 1633b, coal fly ash and ii) GBW07105, rock. Mean elements content spanned from 41870 μg g^− 1 for Fe to 1.14 μg g^− 1 for Lu. The study showed that Fe (41870 μg g^− 1) ? V (1137 μg g^− 1) > Ni (269 μg g^− 1) > Mn (169 μg g^− 1) are the main components. An enrichment, with respect to crustal average, in many elements was observed especially for As, V and Sb that deserve particular interest from the environmental and human health point of view.     

Development of a new open-tubular capillary electrochromatography method for in vitro monitoring of toxic aromatic amines distribution in rat blood

Exposure to aromatic amines from different industrial and agricultural activities entails a substantial risk of deleterious somatic effects, genetic damage and cancer development. Thus, a new and simple method for separation and analysis of aromatic amines has been developed by open-tubular capillary electrochromatography with a novel amphipathic block copolymer (poly(tert-butyl acrylate)(127)-block-poly(glycidyl methacrylate)(86)) coating based on its self-assembled property. Key factors affecting the separation efficiency of the test analytes, such as pH, buffer concentration and selective solvent, were studied in detail. Meanwhile, method validation was well evaluated by linearity (≥0.998), detection limit and recovery. Application of this developed protocol on in vitro monitoring of the target aromatic amines distribution in rat blood demonstrated its potential usage for separation and determination of aromatic amines in biological samples. Additionally, for assimilating more polymeric materials into analysis of aromatic amines, the effect of morphology changes of the amphipathic block copolymer coating on open-tubular capillary electrochromatography separation was also studied, and the result revealed that the block copolymer coating could play the same role as surfactant.     

Determination of Trace Elements in Arsenic and Antimony Minerals by Atomic Absorption Spectrometry and k0-Instrumental Neutron Activation Analysis After Removal of As and Sb

The content of trace elements in arsenic and antimony minerals from the Allchar mine, Macedonia, was determined by electrothermal atomic absorption spectrometry (ETAAS) and k₀-instrumental neutron activation analysis (k₀-INAA) after removal of arsenic and antimony. Their direct determination by ETAAS or k₀-INAA in arsenic (realgar and orpiment) and antimony (stibnite) minerals is limited by strong matrix interferences from As and Sb. Successful elimination of both elements was realized by the extraction of their iodide complexes into toluene. It was found that the optimal conditions were triple extraction of arsenic into toluene from 6mol·L^–1 HCl with addition of KI. Triple extraction of antimony was most successful in the system 4.5mol·L^–1 H₂SO₄ and KI into toluene. In both cases, trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were then detected in the aqueous phase by ETAAS. The proposed procedures with ETAAS were checked by the method of standard additions and Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn determined in realgar, orpiment and stibnite. Using k₀-INAA the trace elements Ba, Ce, Co, Cr, Cs, Fe, Hg, Sc, Tb, Th, U and Zn in realgar and orpiment were determined before and after As and Sb removal from the same aliquot of sample. The removal of both elements with KI into toluene was higher than 99.8% and no losses of trace elements were observed.     

The Pnictogen Bond: The Covalently Bound Arsenic Atom in Molecular Entities in Crystals as a Pnictogen Bond Donor

In chemical systems, the arsenic-centered pnictogen bond, or simply the arsenic bond, occurs when there is evidence of a net attractive interaction between the electrophilic region associated with a covalently or coordinately bound arsenic atom in a molecular entity and a nucleophile in another or the same molecular entity. It is the third member of the family of pnictogen bonds formed by the third atom of the pnictogen family, Group 15 of the periodic table, and is an inter- or intramolecular noncovalent interaction. In this overview, we present several illustrative crystal structures deposited into the Cambridge Structure Database (CSD) and the Inorganic Chemistry Structural Database (ICSD) during the last and current centuries to demonstrate that the arsenic atom in molecular entities has a significant ability to act as an electrophilic agent to make an attractive engagement with nucleophiles when in close vicinity, thereby forming σ-hole or π-hole interactions, and hence driving (in part, at least) the overall stability of the system’s crystalline phase. This overview does not include results from theoretical simulations reported by others as none of them address the signatory details of As-centered pnictogen bonds. Rather, we aimed at highlighting the interaction modes of arsenic-centered σ- and π-holes in the rationale design of crystal lattices to demonstrate that such interactions are abundant in crystalline materials, but care has to be taken to identify them as is usually done with the much more widely known noncovalent interactions in chemical systems, halogen bonding and hydrogen bonding. We also demonstrate that As-centered pnictogen bonds are usually accompanied by other primary and secondary interactions, which reinforce their occurrence and strength in most of the crystal structures illustrated. A statistical analysis of structures deposited into the CSD was performed for each interaction type As···D (D = N, O, S, Se, Te, F, Cl, Br, I, arene’s π system), thus providing insight into the typical nature of As···D interaction distances and ∠R–As···D bond angles of these interactions in crystals, where R is the remainder of the molecular entity.     

Nanoscale structural order from the atomic pair distribution function (PDF): There's plenty of room in the middle

Emerging materials of scientific and technological interest are generally complex and often nanostructured: they have atomic orderings that extend on nanometer length-scales. These can be discrete nanoparticles; bulk crystals with nanoscale chemical or displacive order within them; mesoporous materials that are bulk materials containing nanoscale holes; and nanocomposites that are intimate heterogeneous mixtures of nano-sized constituents. As always, a quantitative knowledge of the atomic structure within these materials is a prerequisite to understanding and engineering their properties. Traditional crystallographic methods for obtaining this information break down at the nanoscale, sometimes referred to as “the nanostructure problem”. We describe here some emerging methods for studying nanoscale structure. We present some examples of recent successes. Finally, we discuss future directions and opportunities and draw attention to limitations and potential problems.     

Hepatobiliary excretion and brain distribution of caffeine in rats using microdialysis

To investigate the pharmacokinetic mechanism of hepatobiliary excretion and brain distribution of caffeine, this study uses a method based on microdialysis technique and liquid chromatography that allows continuous and concurrent in vivo monitoring of extracellular caffeine in the blood, brain and bile of anesthetized rats following the administration of caffeine (3 or 10 mg/kg, i.v.) through the femoral vein. Dialysates of the blood, brain and bile were directly injected onto the liquid chromatographic system and no further clean-up procedures were required. The study design consisted of two groups of six rats in parallel: the rats of the control group received caffeine (3 or 10 mg/kg, i.v.) alone and those of the cyclosporine treated-group were injected cyclosporine (10 mg/kg, i.v.) 10 min prior to caffeine administration (3 or 10 mg/kg, i.v.). The decline of caffeine in the blood, brain striatum and bile suggested that caffeine had rapid exchange and equilibration between the peripheral compartment and the central nervous system. In addition, the results indicated that caffeine underwent hepatobiliary excretion and was distributed into brain. When cyclosporine was co-administered, the pharmacokinetic parameters were not significantly altered. The results of this study reveal that the pharmacokinetic mechanism of hepatobiliary excretion and brain distribution of caffeine might not relate to P-glycoprotein.     

Application of a liquid chromatography–tandem mass spectrometry method to the pharmacokinetics,tissue distribution and excretion in the study of anemoside B4, a novel antiviral agent candidate,in rats

A simple, sensitive and reliable LC–MS/MS method was developed and validated for the quantification of anemoside B4, a potential antiviral constituent isolated from Pulsatilla chinensis in rat plasma, tissue, bile, urine and feces. All biological samples were prepared by protein precipitation method, and ginsenoside‐Rg1 was chosen as the internal standard (IS). The analyte and IS were separated using a C₁₈ column (2.1 × 50 mm, 1.8 μm) and a mobile phase consisting of 0.1% formic acid in water (v /v) and acetonitrile running at a flow rate of 0.2 mL/min for 5 min. The multiple reaction monitoring transitions were monitored at m /z 1219.5–749.5 for anemoside B4 and 845.4–637.4 for ginsenoside‐Rg1 in electrospray ionization negative mode. The calibration curve was linear in the range of 10–2000 ng/mL for all biological matrices with a lower limit of quantification of 10 ng/mL. The validated method was successfully applied to a pharmacokinetics, tissue distribution and excretion study. These preclinical data will be beneficial for further development of anemoside B4 in future studies.     

The profiling and identification of the metabolites of 8‐prenylkaempferol and a study on their distribution in rats by high‐performance liquid chromatography with diode array detection combined with electrospray ionization ion trap time‐of‐flight multistage mass spectrometry

8‐Prenylkaempferol is a prenylflavonoid that has various bioactivities and benefits for human health. A high‐performance liquid chromatography with a diode array detector combined with electrospray ionization ion trap time‐of‐flight multistage mass spectrometry (HPLC‐DAD‐ESI‐IT‐TOF‐MSⁿ) method was established to profile and identify the metabolites of 8‐prenylkaempferol in rat in vivo and in vitro, and to study the distribution of these metabolites in rats for the first time. A total of 38 metabolites were detected and tentatively identified, 30 of which were identified as new compounds. The new in vivo metabolic reactions in rats of prenylflavonoids of isomerization, polymerization, sulfation, amino acid conjugation, vitamin C conjugation and other known metabolic reactions were found in the metabolism of 8‐prenylkaempferol. The numbers of detected metabolites in feces, urine, plasma, small intestine, stomach, kidneys, liver, heart, lungs, spleen and hepatic S9 fraction were 31, 19, 1, 20, 13, 8, 7, 3, 3, 1 and 11, respectively. This indicated that small intestine and stomach were the major organs in which the 8‐prenylkaempferol metabolites were distributed. Furthermore, 16 metabolites were determined to have bioactivities based on the literature and ‘PharmMapper’ analysis. These findings are useful for better comprehension of the effective forms, target organs and pharmacological actions of 8‐prenylkaempferol. Moreover, they provide a reference for the study of the metabolism and distribution of prenylflavonoid aglycone compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Determination of molecular orientation distribution of a stable paramagnetic probe in oriented 4-cyano-4’-<Emphasis Type="Italic">n</Emphasis>-pentylbiphenyl

The molecular orientation distribution function of a stable radical 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl in magnetic-field oriented 4-cyano-4’-n-pentylbiphenyl was determined from the angular dependence of the ESR spectra. The preferred molecular orientation of radical species in the liquid crystal matrix was determined. The temperature evolution of the orientation distribution function was studied.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 190–195, January, 2005.