Determination of trace elements in inorganic and organic materials by x-ray fluorescence spectroscopy

A new, almost universally applicable method for the trace analysis of inorganic and organic materials is described. The trace element (or elements) together with a suitable coprecipitating element is isolated from interfering elements by precipitation with a suitable organic or inorganic precipitant. The precipitate is then filtered on a paper disk and the collected trace element (or elements) is determined by X-ray analysis.     

Multielement photon activation analysis of biological materials.

A non-destructive photon activation procedure with 30-MeV bremsstrahlung followed by high-resolution γ-spectrometry is proposed for multielement analysis of biological materials. The materials tested were the NBS SRM Orchard Leaves and Bovine Liver, Bowen′s kale and Kentucky 1R1 tobacco standards. Simultaneous irradiation of the sample with synthetic multielement standards containing 25 elements showed that up to 12 elements can be determined in a single sample. The method is quite simple and gives good reproducible results. Agreement of the results with published data is excellent.     

Determination of strontium in biological materials by charged-particle activation analysis using the stable isotope dilution method

In order to apply the stable-isotope dilution method to charged-particle activation analysis, determination of strontium in biological materials has been studied by proton activation using isotopically enriched⁸⁶Sr as a spike. To avoid thermal decomposition of biological materials due to the low penetrating power of proton beam, and to eliminate interfering nuclear reactions due to the matrix elements, strontium in the sample and/or isotopic mixture as a comparator was separated chemically together with most of calcium before bombardment, and the fraction isolated was converted to a silica-gel pellet as a most suitable physical and chemical form for bombardment. By processing as above, it was demonstrated that the strontium contents in the biological materials can be determined accurately, precisely and easily. Through a series of experiments, the method was also proved to be applicable for charged-particle activation analysis.     

Simultaneous analysis of bisphenol A based compounds and other monomers leaching from resin‐based dental materials by UHPLC–MS/MS

Resin‐based dental materials have raised debates concerning their safety and biocompatibility, resulting in a growing necessity of profound knowledge on the quantity of released compounds into the oral cavity. In this context, the aim of this study was to develop a comprehensive and reliable procedure based on liquid chromatography with mass spectrometry for the simultaneous analysis of various leached compounds (including bisphenol A based compounds) in samples from in vitro experiments. Different experiments were performed to determine the optimal analytical parameters, comprising mass spectrometry parameters, chromatographic separation conditions, and sample preparation. Four internal standards were used as follows: deuterated diethyl phthalate and bisphenol A (commercially available), and deuterated analogues of triethylene glycol dimethacrylate and urethane dimethacrylate (custom‐made). The optimized method was validated for linearity of the calibration curves and the associated correlation coefficient, lower limit of quantification, higher limit of quantification, and intra‐ and interassay accuracy and precision. Additionally, the developed liquid chromatography with tandem mass spectrometry method was applied to the analysis of leaching compounds from four resin‐based dental materials. The results indicated that this method is suitable for the analysis of different target compounds leaching from dental materials. This method might serve as a valuable basis for quick and accurate quantification of leached compounds from resin‐based dental materials in biological samples.     

“Do it yourself” reference materials for δ 13C determinations by isotope ratio mass spectrometry

A method is described to prepare inexpensive organic reference materials for routine stable isotope work. The method blends isotope-enriched and isotope-depleted materials to match closely international measurement standards. Examples are presented showing how ¹³C-enriched and ¹³C-depleted glucose were blended to match the isotopic compositions of the international carbon isotope standards, NBS 19 and L-SVEC. Preparation of the blended standards was straightforward, and the prepared solutions proved easy to dispense into tin capsules and easy to combust in a conventional isotope analysis system. The blended materials allow a laboratory to perform a two-point calibration for isotopic composition on a daily basis, with the use of an international reference material recommended for routine quality assurance. The blending method can be applied widely to make isotope standards for other elements and compounds.     

Input of missing trace elements in some IAEA/NBS biological certified reference materials using INAA

IAEA and NBS biological certified reference materials have been analyzed by instrumental neutron activation analysis and concentration of 17 elements was determined. The elements determined were either completely missing or their certified values were not given in the original compilations. For quality assurance of our work, a comparison of data on missing trace elements in some of the CRMs has been presented. It seems that second round of analysis for the certification of these elements would be useful.     

标准溶液配制用碳酸锂纯物质中杂质含量的测定

从高纯碳酸锂中杂质含量测定出发,研讨了标准溶液配制用原料的杂质测定方法,首先利用电感耦合等离子体质谱(ICP-MS)法对高纯碳酸锂进行半定量分析,再依据半定量分析结果选择ICP-MS、电感耦合等离子体原子发射光谱(ICP-AES)法、原子吸收光谱(AAS)法等方法对相应元素(杂质含量0.001%)进行定量分析,通过扣除杂质含量得出高纯碳酸锂纯度大于99.991%。从而建立了一个准确、高效,覆盖元素种类多的高纯物质中杂质含量的分析方法     

Determination of impurities in uranium oxide by inductively coupled plasma mass spectrometry (ICPMS) by the matrix matching method

An analytical procedure was developed to determine the concentration of some elements regarded as trace impurities in nuclear fuel using inductively coupled plasma mass spectrometry (ICPMS) associated to the matrix matching method. The assessment of this approach was carried out using a set of certified reference materials produced by the New Brunswick Laboratory (NBL). Eighteen out of the twenty-four elements in the reference materials could be easily determined. It was found that the mean values for reproducibility and accuracy were 5.0% and 15.0%. The remaining six elements provided mean values of 11.0% and 37.0%, respectively. They could not be adequately determined due to the effects of analyte signal suppression and spectral interference.     

封闭压力酸溶-盐酸提取-电感耦合等离子体原子发射光谱法(ICP-AES)测定页岩中的多种微量金属元素

采用高温、高压消解罐法前处理页岩矿石样品,电感耦合等离子体原子发射光谱法(ICP-AES)测定了页岩标准物质中的多种微量元素的含量。实验过程中确定了最佳工作条件,选择了最佳分析谱线。实验结果表明,该方法线性相关系数良好r0.999 8,方法检出限低,精密度高,RSD小于3.0%,可同时测定页岩矿石中的多种金属元素,方法完全能满足岩石、土壤、沉积物中多种元素的检测需求。     

Determination of trace elements in semiconductor materials by neutron activation analysis using the radioisotope addition technique

The determination of trace elements in highly activated matrix components was carried out by neutron activation analysis using the radioisotope addition technique. The method is based on the addition to the irradiated test sample of a radioisotope which is a diffeent nuclide of the element to be determined. After separation, the chemical yield is calculated from the radioactivity added and the element is determined by an ordinary technique. Twelve elements in indium phosphide and eight elements in gallium arsenide could be determined by the method.     

A new method for the determination of oxygen in organic compounds

Oxygen in compounds of carbon, hydrogen, and oxygen can be determined by heating the sample with an excess of strontium oxide and graphite in. a nickel bomb or sealed Vycor glass tube. During the heating period, three hours at 650° C, the oxygen of the sample is converted to carbonate. The carbonate is then determined volumetrically. The accuracy of the method was found to be ± 0.3% (absolute percentage error) for several types of compounds. Most elements other than carbon, hydrogen, and oxygen interfere. Compounds like phenol, that are exceedingly resistant to complete pyrolysis, yield low resuilts. Carbon in organic compounds can be determined by heating the sample with barium nitrate, and subsequently determining carbonate in the mixture.     

Lower limit of determination values for trace elements in iron certified reference materials by neutron activation analysis with multiple gamma-ray detection

Recycling steel products demands a new technique for determining tramp elements in steel. Tramp elements, As and Sb, in some iron certified reference materials were determined by neutron activation analysis with multiple gamma-ray detection method and reported in MTAA11. In MTAA12, the authors reported the lower limit of determination values (LDL) and the dispersion of this method. The values of the LDLs for As and Sb in high purity iron were 0.002 and 0.0009 μg·g⁻¹. The dispersion is small enough to satisfy the demand from materials science.     

The application of INAA in a study of environment geochemistry on the Xizang (Tibet) Plateau,China

INAA as a routine analysis method has been used in a study of environment geochemistry on the Xizang (Tibet) Plateau in China, and 34 elements in soil samples were determined by INAA with both short and long irradiations. This paper presents some primary results from the study, including mean element concentrations in Tibetan soil, paterns of element distribution in soils developed from main types of parent materials on the plateau. The results confirm the expectation that soil formed in such cold and dry environment on the plateau retained the main geochemical characteristics of the parent materials. However, the results still imply the possible migration of some elements in different bio-climatic environments during the soil formation. The elements in the top soils, mainly the alkalis and alkaline earths, and also As, Br, etc., were enriched or depleted in varying degrees in proportion to their abundance in the parent materials.     

Rational Combination of the Dissolution of Some Inorganic Compounds of Rare-Earth Elements with the Determination of Chemical Forms of Major Constituents in These Compounds

It was found that the major constituents (F^– and S^2–) in fluorides, sulfides, and sulfofluorides of rare-earth elements, and europium(II) in europium fluoride, can be determined titrimetrically. Peculiarities of the decomposition and analysis of initial samples of these compounds and samples after high-temperature treatment in vacuum were considered. The analytical procedures are based on the combination of the decomposition of the test materials using solutions of iodine (determination of S^2–), boric acid (determination of F^–), and vanadium(V) salts (determination of europium(II) salts) and the final titration of excess reagents that selectively reacted with a chemical form of the analyte. Potentiometry with an ion-selective electrode was also used in the determination of fluoride ions. The total concentration of rare-earth elements was determined by chelatometry.     

Elemental analysis of organo-metallic compounds The simultaneous determination of carbon, hydrogen and other elements in one weighed sample

A method is described for simultaneous gravimetric microdetermination of carbon, hydrogen and one or more heteroelements in one weighed sample of organic substances. The method is based on pyrolytic combustion of the sample in a quartz container placed in an empty combustion tube. The carbon and hydrogen determination is completed as usual. Hetero-elements, in the form of volatile compounds, are retained in special previously weighed tubes inside the combustion tube. Hetero-elements forming non-volatile residues can be determined by the change in weight of the quartz sample-container. Volatile elements or compounds are determined by weighing the quartz insert tube. More than 40 elements in various combinations can be determined simultaneously with carbon and hydrogen.     

New Developments in Activation Analysis for Material and Environmental Sciences

Activation analysis in general and mainly reactor neutron activation analysis (NAA) has been used extensively for measuring trace elements in high purity materials, particularly semiconductor materials. The advantages of NAA in determination of trace elements differ from one semiconductor material to another. For all of them the inherent properties of activation analysis especially those of non contamination with the reagents, low blanks and high sensitivity are the reasons for the choice of NAA as the main analytical procedure. These inherent properties are essential for analysis of high-purity materials where concentrations of ppb's and sub ppb's have to be measured. NAA is specially suitable for the determination of trace elements in silicon due to the very short lived very low activity induced by neutron reaction in silicon. This enables easy instrumental (i.e. without chemical separations) determination of trace elements in silicon. In the HFR reactor at Peten, Netherlands, a special facility was constructed for irradiation of silicon samples of Philips, in which silicon wafers of up to 15 cm diameter can be irradiated with 4 × 10¹³n. cm^?2. sec^?1 and the irradiation is done for 72–96 hours. using large Ge(Li) detectors (100 to 150cc) and long counting time (8–16 hours) they measured 22 elements in concentrations below ppb and 10 others between ppb and 300 ppm. Trace elements in germanium have been determined both instrumentally after very long decay time (100 days) or after short decay time removing the activities from the matrix by chemical separation. Trace elements in GaAs are determined only after chemical separtion. Several other semiconductor material such as Sc, Te, GaP and CuInS₂ were also determined by NAA. Some trace elements cannot be determined by neutron activation. Carbon, nitrogen and oxygen are determined by activation with protons, alphas or ³He particles. Boron and hydrogen are determined by prompt emission induced by charged particle activation, which gives not only the total concentration but also the depth profile. Carbon, nitrogen, oxygen and phosphorus were also determined by prompt proton activation analysis. The environmental samples studied by activation analysis can be divided into three categories: atmospheric aerosols, water samples and solid wastes. NAA of atmospheric aerosols have been used for their posible toxicological hazards, their source identification and for studies of atmospheric transport processes.     

Low temperature synthesis of zinc ferrite nanoparticles

Zinc ferrite (ZnFe₂O₄) nanocrystalline powder materials with various particle sizes were prepared by a unique solid-state combustion method. Phase purity of ZnFe₂O₄ was confirmed by X-ray diffraction studies. High resolution transmission electron microscopic analysis and selected area diffraction pattern also confirmed the correct crystalline phase formation. Particle size was determined from both the transmission electron microscopic images and also from the XRD peak broadening analysis. Oxidation states of different elements present in ZnFe₂O₄ were determined by X-ray photoelectron spectroscopy. Frequency dependent dielectric constant and a.c. conductivity were measured as a function of particle size and both of them were found to decrease with decreasing particle size. These studies indicated that good quality zinc ferrite nanocrystalline powdered materials can be synthesized at low temperature.     

Separation scheme for the determination of alkali metals (K, Rb, Cs), alkaline earths (Sr, Ba) and rare earths (Ce, Nd, Sm, Eu) in silicate materials by isotopic dilution analysis

A scheme is outlined for the separation of Li, K, Rb, Cs, Sr, Ba, Ce, Nd, Sm and Eu from silicate materials. The elements are separated by cation-exchange to provide groups suitable for mass spectrometric analysis, and are then further purified by anion-exchange. Results obtained by isotopic dilution analysis are reported for G-1, W-1, and the Harwell meteorite-in these measurements the alkali metals were determined separately from the other elements. Requirements are discussed for combining the procedures to form a more comprehensive method for use with a single sample.     

Study on the comparator method using substoichiometry

The comparator method using substoichiometry is developed. In the method, the contents of the elements can be determined simultaneously by the measurement of radioactivities of the comparator elements and of simultaneously separated parts of the elements in question. The method is applied to the simultaneous determination of rare earth elements, such as lanthanum, europium and terbium in NBS botanical standard reference materials. It is confirmed that the method is reliable for simultaneous multielement determination.     

Analysis of Europium,Yttrium and Lanthanum Compounds by Atomic Emission Spectrometry with Inductively Coupled Plasma

The paper presents a multi-element analysis of europium, yttrium and lanthanum compounds by atomic emission spectrometry with inductively coupled plasma (ICP-AES). The plasma power was optimized, the choice of analytical lines of the impurities to be determined and the concentration of matrix element were substantiated. The method allows to determine up to 40 trace elements with the limits of detection (LODs) ranging from 10^–6 to 10^–3 wt %.