Graphite furnace atomic absorption spectrometry for the analysis of biological materials

Graphite furnace atomic absorption spectrometry (GFAAS) is used to analyze a variety of biological materials. Conventional single element determinations as well as multielement determinations made on the SIMAAC are discussed. Four sample preparation methods were used to prepare samples for GFAAS including: direct analysis of liquids, wet ashing, dry ashing, and slurry preparation. Results from analyses of a wide variety of materials are presented.     

Total-Reflection X-ray fluorescence analysis of elements in size-fractionated particulate matter sampled on polycarbonate filters — Composition and sources of aerosol particles in Göteborg,Sweden

This is the first study applying the technique of cold plasma ashing on polycarbonate filters as a preparative step for subsequent elemental analysis of aerosol particles by Total-Reflection X-ray fluorescence. The procedure has been validated by analyzing blanks of the filter material, chemicals used as additives as well as certified standard reference material. The results showed that cold plasma ashing is superior to conventional digestion methods with regard to the ease of sample preparation and contamination. A PIXE cascade impactor was used to collect size-fractionated aerosol particles in 9 size classes ranging from 16 to 0.06 µm aerodynamic diameter at an urban and a suburban site in Göteborg, Sweden. Filter segments loaded with the aerosol particles were cut out and fixed on Quartz carriers. After adding 10 ng of Ga as internal standard the samples were dried, digested by cold plasma ashing and analyzed by Total-Reflection X-ray fluorescence. The analysis of aerosol particles showed that elemental concentrations at both the urban and the suburban site in Göteborg were low compared to central Europe. More and concurrent sampling of size-fractionated particles is required to identify local sources of trace elements in the urban area of Göteborg.     

Determination of calcium, potassium, manganese, iron, copper and zinc levels in representative samples of two onion cultivars using total reflection X-ray fluorescence and ultrasound extraction procedure

The chemical characterization of onion cultivar samples is an important tool for the enhancement of their productivity due to the fact that chemical composition is closed related to the quality of the products. A new sample preparation procedure for elemental characterization is proposed, involving the acid extraction of the analytes from crude samples by means of an ultrasonic bath, avoiding the required digestion of samples in vegetable tissue analysis. The technique of total reflection X-ray fluorescence (TXRF) was successfully applied for the simultaneous determination of the elements Ca, K, Mn, Fe, Cu and Zn. The procedure was compared with the wet ashing and dry ashing procedures for all the elements using multivariate analysis and the Scheffé test. The technique of flame atomic absorption spectrometry (FAAS) was employed for comparison purposes and accuracy evaluation of the proposed analysis method. A good agreement between the two techniques was found when using the dry ashing and ultrasound leaching procedures. The levels of each element found for representative samples of two onion cultivars (Yellow Granex PRR 502 and 438 Granex) were also compared by the same method. Levels of K, Mn and Zn were significantly higher in the 438 Granex cultivar, while levels of Ca, Fe and Cu were significantly higher in the Yellow Granex PRR 502 cultivar.     

TXRF法测定松花粉中的9种生命元素

建立了微波消解前处理,全反射X射线荧光法(TXRF)同时测定松花粉中K、Ca、Ti、Mn、Fe、Ni、Cu、Zn和Rb9种生命元素含量的分析方法.松花粉原料经过微波消解前处理后,采用全反射X射线荧光光谱净计数、QXAS分析软件解谱和单一内标法进行定量分析.比较了干灰化法、湿消解法和微波消解法3种前处理方法的效果,并确立微波消解法作为样品前处理方法.用微波消解- TXRF法测定了花粉标准物质中的上述9种元素,并计算得到其仪器检出限(LLD)为0.002～0.054 mg/L,方法检出限(LDM)为0.004～0.122 mg/kg.TXRF法测定各元素的相对标准偏差(RSDs)为1.0％～5.5％.该方法操作简单、样品用量少、检出限低,对实际样品松花粉的测定结果与ICP - MS法无显著性差异.     

粉末压片X射线荧光光谱法测定铌铁合金中 铁、铌、硅、铝、磷

为提高铌铁合金检验效率,替代繁琐的化学湿法分析,采用粉末压片制样,利用X荧光光谱法对铌铁合金中Fe、Nb、Si、Al、P 5种主要成分进行测定。选用定值过的生产样品作为内控标准样品,主要研究制样细节对分析结果的影响,确认合适的试样粒度和压片参数,通过曲线拟合建立校准曲线。测定结果与化学湿法和电感耦合等离子体原子发射光谱法测定结果比较,各组分精密度相对标准偏差为0.48%～1.9%,准确度满足国标分析要求。     

Development of a Unified X-ray Fluorescence Procedure for Determining Heavy Metals in Biological Materials

A unified procedure for the X-ray fluorescence determination of Pb, Mo, Rb, As, Zn, Ni, Fe, and Mn in biological materials was developed using the internal standard technique (gallium was the reference element). The samples were prepared for analysis by ashing the materials. The effects of variations in the chemical composition and of the surface density of unsaturated radiators on the accuracy of the analytical results were studied with the use of theoretical intensities; this effect varied from 2.5 to 22%. Based on this information, an optimum calibration function was chosen. Ashes of plant and animal tissues can be analyzed with the use of this function. The errors due to sample preparation for analysis and the reproducibility and accuracy of the results of X-ray fluorescence analysis were evaluated.     

不同灰化温度下生物质混煤灰的烧结特性研究

选取晋城无烟煤和麦秆作为研究对象,利用压差法烧结温度测定装置测量不同灰化温度下煤和麦秆混合灰的烧结温度,再利用SEM-EDS以及XRD对灰样进行烧结特性分析。结果表明,不论灰化温度高低,随着麦秆的添加,煤和麦秆混合灰的烧结温度都呈现降低趋势,其降低幅度略有差别。灰化温度较低时,煤和麦秆混合灰的烧结温度低于灰化温度较高情况下混合灰的烧结温度。SEM-EDS分析表明,低温灰化得到的样品中出现较多不规则的纤维结构;较高温度下获得的灰样中出现较多致密的球状颗粒,这表明矿物质发生熔融形成球状颗粒。XRD分析表明,低温灰化烧结后的煤和麦秆混合灰样中因含有较多的含钾等碱金属系助融矿物质,导致混合灰样的烧结温度降低。然而,像钙长石等含钙矿物质本身具有较高的熔点,因此,在1 100℃时混合灰样具有较高的烧结温度。     

X射线荧光光谱法测定黑龙江省有机碳含量较高样品中的硅、铝、铁等元素

通过事先对有机碳含量较高的样品进行高温灼烧,计算其烧失量,再将灼烧后的样品经专用熔剂熔融制样后,经X射线荧光光谱仪测定,能够有效地去除因有机质含量高导致的分析结果的偏差,而且较湿法化学分析节省时间。实验结果表明,该方法的分析结果与湿法化学分析结果偏差很小,准确度较直接压片分析有了大幅提高。     

虾粉中总砷测定方法的探讨

用氢化物原子荧光光度法测定虾粉中总砷含量时,对干法灰化、湿法消解、微波消解3种样品处理方法对虾粉中砷元素测定结果的影响进行了比较。通过试验确定了最佳消解条件。砷元素浓度在0~10μg/L的范围内与荧光强度呈线性关系,线性相关系数r=0.999 6,检出限为0.2μg/L。比对结果表明,干法灰化适合于测定虾粉中总砷的含量,湿法消解测定总砷的含量偏低,微波消解不适合测定虾粉中总砷的含量。采用干法灰化-氢化物原子荧光光度法测定虾粉中总砷含量,加标回收率为76.2%~106.0%。     

Honey as an environmental indicator: Effect of sample preparation on trace element determination by ICP-AES

Trace element concentrations in honey collected from a wide area can be used as an environmental indicator, but sample preparation methods prior to analysis can have large effects on the results. The efficiency and reproducibility of sample preparation methods (dilution, ashing and digestion) for simultaneous multi-element analysis have been compared for 13 elements. Digestion in a PTFE bomb was found to be the most reliable method.     

The University of Surrey&;#39;s new proton microprobe and the feasibility of PIXE-tomography for trace element analysis of biological tissues

Summary The University of Surrey Ion Beam Centre has recently installed a tandem accelerator with a new proton microprobe and the potential for sub-micron beam-spot size. The facilities for Nuclear Microscopy (NM), combining scanning transmission ion microscopy/tomography (STIM-T) and proton induced X-ray emission tomography (PIXE-T) of biological tissues are being developed. This paper will review developments in ion beam tomography of biological samples and methods in accurately producing trace-elemental maps that are meaningful. Cell composition and integrity can be seriously compromized by the preparation of the sample and by beam-induced damage, causing loss of matrix elements as well as a change in cell size. Beam-induced damage, determination of 3-dimensional X-ray attenuation and secondary fluorescence contribute to the complex nature of the reconstruction and interpretation of PIXE-tomographic data. A PIXE, STIM and Rutherford backscatter analysis of leukocytes is presented in part to test the new microprobe but also to identify areas of improvement in facilities at the university and nuclear microscopy in general, in anticipation of producing maps for more direct biological and medical research.     

Sapphire sample carriers for silicon determination by total-reflection X-ray fluorescence analysis

Sapphire is presented as a new sample carrier material for total-reflection X-ray fluorescence spectrometry (TXRF). A comparison with conventional sample carrier materials such as quartz glass, Perspex®, glassy carbon and boron nitride demonstrates that sapphire has all the physical and chemical properties required for TXRF micro and trace analysis. Moreover, sapphire sample carriers allow the determination of silicon in many matrices in a comparatively simple way. Especially for airborne particulate matter, acid digestion can be avoided by cool-plasma ashing of suitable filter materials directly on the sample carrier. This technique has been successfully applied to environmental samples.     

Preconcentration and x-ray fluorescence : Determination of vanadium,nickel and iron in residual fuel oils and in particulate material from oil-fired sources

X-ray fluorescence spectrometry after dithiocarbamate preconcentration is described for the determination of vanadium, nickel and iron in residual fuel oils and in small amounts of particulate emissions from oil-fired sources. After the sample has been decomposed by dry ashing or wet digestion, the metal constituents are concentrated as their diethyldithiocarbamates precipitates on a membrane filter for measurement. The method is simple and highly sensitive, and the analytical results are in good agreement with certified values or with the results obtained by solution spectrophotometry.     

Characterization of small particles by micro X-ray fluorescence

Micro X-ray fluorescence was used to study both homogeneous and heterogeneous particle systems. Specifically, homogeneous glass microspheres and heterogeneous soil particle samples were prepared by both bulk and single particle sample preparation methods for evaluation by micro X-ray fluorescence. Single particle sample preparation methods allow for single particles from a collected sample to be isolated and individually presented to the micro X-ray fluorescence instrument for analysis. Various particle dispersion methods, including immobilization onto Tacky Dot™ slides, mounting onto double-sided sticky tape affixed to polypropylene film, or attachment to polypropylene film using 3M Artist's Adhesive, were used to separate the sample particles for single particle analysis. These methods were then compared and evaluated for their ability to disperse the particles into an array of single separated particles for optimal micro X-ray fluorescence characterization with minimal background contribution from the particle mounting surface. Bulk methods of particle sample preparation, which included pellet preparation and aerosol impaction, used a large quantity of collected single particles to make a single homogeneous specimen for presentation to the instrument for analysis. It was found that single particle elemental analysis by micro X-ray fluorescence can be performed if the particles are well separated (minimum separation distance = excitation source beam diameter) down to a particle mass of ∼ 0.04 ng and a mean particle diameter of ∼ 0.06 μm. Homogeneous particulates can be adequately characterized by micro X-ray fluorescence using either bulk or single particle analysis methods, with no loss of analytical information. Heterogeneous samples are much harder to characterize, and both single particle as well as bulk analyses must be performed on the sample to insure full elemental characterization by micro X-ray fluorescence.     

High pressure transformations in zinc silicates

Phase transformations in Zn₂SiO₄ and ZnSiO₃ have been investigated at high pressure up to 170 kbar and temperature to 1500°C. Crystal structures of high pressure polymorphs have been studied by means of single crystal and powder X-ray diffraction analyses. Chemical compositions have been determined by electron microprobe and wet chemical analyses.     

Micro Dry Ashing for Trace Selenium Determination in Organic Matrices

Abstract

A specific sample treatment method was established for determination of ng levels of Selenium in microquantities of organic compounds. Our task was determination of Selenium traces, in a new pharmaceutical product, as a result of a laboratory scale synthesis, in an amount of several tens of mg. GFAAS was chosen as an analysis method, due to its sensitivity and rapidity. Among the wet and dry methods for organic material digestion tried, the low temperature dry ashing using ashing aid, was the only one which gave satisfactory recoveries of Selenium. Micro dry ashing was performed, using an Ethanol solution of Magnesium Nitrate on samples spiked with Selenium Nitrate in the range of concentration of 1–6ng mg^?1 at a temperature of 450°C for two hours. The presence of Magnesium Nitrate and the heating suppress the atomization with approximately 15–25%. Recoveries of Selenium varies as a function of the organic matrix: for polyaromate compounds as Chrysene and Fluoranthene they lie between 90–103% and for oxygenated compounds as Dimethoxybenzoic acid or Phthalates 23–50% respectively.

Another aspect of chemical interference by organic matrices and the way how to overcome it, has been clarified.     

Quantification of heavy metals for the recycling of waste plastics from electrotechnical applications

Analytical data on element concentrations in plastics is an important prerequisite for the recycling of technical waste plastics. The chemical resistance and high additive contents of such materials place a high demand on analytical methods for quantifying elements in thermoplastics from electrotechnical applications. The applicability of three common independent analytical methods (EDXRF, AAS, ICP-AES) for the quantification of heavy metals in such technical waste plastics of varying composition was studied. Following specific sample pre-treatments, such as closed vessel microwave assisted digestion and wet ashing with H(2)SO(4), three hazardous metals (Pb, Cd, Sb) were determined. Conditions were investigated to minimize matrix effects for all analytical techniques employed. The trueness for the quantification of Cd was checked by using the certified reference material VDA 001-004 (40-400 mug g(-1) Cd in polyethylene), and no significant differences to certified values were found. The best detection limits were found to be 2, 1.3 and 7.9 mug g(-1) for Cd, Pb and Sb, respectively. In technical waste polymers, Sb was detected to be in the range 1-7%, Cd in the range 80-12 000 mug g(-1) and Pb in the range 90-700 mug g(-1). The precision reached for the analysis of this complex material, is comparable for all methods, and can be expressed by a relative standard deviation smaller than 8%. Application of multivariate analysis of variances (MANOVA) showed no differences between the mean results, except for the ICP-AES analysis following wet ashing with H(2)SO(4).     

Determination of the elemental composition of tissues of the cardiovascular system by atomic spectrometry, mass spectrometry and X-ray spectrometry methods

The review discusses the published data on the concentrations of chemical elements in tissues of the cardiovascular system determined by atomic absorption and atomic emission spectrometry, mass spectrometry, and also X-ray fluorescence analysis, proton-induced X-ray emission, and X-ray microanalysis. The main parameters of X-ray spectrometry methods used for the examination of the cardiovascular system are compared, the new trends in the analysis of these samples and the main sample preparation approaches are considered.     

Arsenic determination in certifiable color additives by dry ashing followed by hydride generation atomic absorption spectrometry

The preparations of digested samples of certifiable color additives by dry ashing and wet digestion for arsenic analysis by hydride generation atomic absorption spectrometry (AAS) were compared. The dry ashing technique was based on the preparation used in ASTM D4606-86 for determination of As and Se in coal. The acid digestion method used nitric and sulfuric acids heated by microwaves in sealed vessels. The digested color additives were analyzed for As by using hydride generated from sodium borohydride mixed with the acidified solution on a flow injection system leading to an atomic absorption spectrometer. Dry ashing was preferable to wet digestion because wet digestion yielded poor recoveries of added As. Dry ashing followed by hydride generation AAS gave determination limits of 0.5 ppm As in the color additives. At a specification level of 3 ppm As, the precision of the method using dry ashing was +/- 0.4 ppm (95% confidence interval).