Characterization of Indian Ayurvedic herbal medicines for their metal concentrations using WD‐XRF spectrometry

This article describes the details of metal concentrations evaluated using wavelength dispersive X‐ray fluorescence (WD‐XRF) spectrometry. A total of 22 elements, Na, Mg, Al, Si, P, S, K, Ti, Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Hg, Pb, Ba, Au, and Sn from 16 Ayurvedic medicines were characterized. The method was validated by analyzing the six certified reference materials of soil standards [NIST SRM‐2710, CRM 027‐050 (US‐EPA certified), PS‐1, TILL‐1 and TILL‐4 (Canadian certified reference material, CCRMP) and JSO‐1 (Japanese certified reference material)]. The elemental concentrations in all the standards are found to be within ± 10% of the reported values. Crystalline phases in the individual drug samples were explained by powder X‐ray diffraction (XRD) technique. Qualitative phase identification was done using the ICDD database. Copyright © 2010 John Wiley & Sons, Ltd.     

Quantitative elemental analysis of individual particles with the use of micro‐beam X‐ray fluorescence method and Monte Carlo simulation

The aim of the work was to develop a Monte Carlo (MC) method and combine it with micro‐beam X‐ray fluorescence (XRF) technique for determination of chemical composition of individual particles. A collection of glass micro‐spheres, made of NIST (National Institute of Standards and Technoly) K3089 material of known chemical composition, with diameters in the range of 25–45 µm was investigated. The micro‐spheres were measured in a scanning micro‐beam XRF spectrometer utilising X‐ray tube as a source of primary radiation. Results obtained for low Z elements showed high dependence on particle size. It was found that the root mean square of concentration uncertainty, for the all elements present in the particle, increases with growing sample size. More accurate results were obtained for high Z elements such as Fe–Pb, as compared to others. The elemental percentage uncertainty did not exceed 14% for any particular sample and 6% for the whole group of the measured micro‐spheres as an average. Results obtained by the Monte Carlo method were compared with other analytical approaches. Copyright © 2009 John Wiley & Sons, Ltd.     

XRF和LA-ICPMS测定硫化物熔片中的主次量元素

采用高纯HNO₃为氧化剂代替传统的氧化剂,以GeO₂为玻璃化试剂,建立了一种简单、高效的硫化物熔融玻璃片的前处理方法。XRF和LA-ICPMS分析结果表明,相对于粉末压片法,熔片法制备的样品具有更好的均一性和可靠性。3种硫化物国家一级标准物质的XRF和LA-ICPMS主次量元素(Si,Al,Fe,Mg,K,Ca,Na,Mn,Cu,Zn)分析测试结果均与推荐值相吻合(Ti缺少推荐值),测定误差都在允许范围内,XRF三次熔片测试结果的精密度RSD<5.6%;LA-ICPMS 15次测试结果精密度RSD<3%。表明建立的硫化物熔融玻璃片的前处理方法可较好的应用于XRF和LA-ICPMS分析硫化物中的主次量元素。     

X‐ray fluorescence spectrometry in Dar es Salaam

Energy‐dispersive x‐ray fluorescence (EDXRF) analysis has been established at the University of Dar es Salaam, Faculty of Science, Department of Physics. Calibration was conducted using thin films from Micromatter (USA) for secondary target XRF. We report on the performance of the spectrometer including the detection limits attained, which range from 0.01 to 10 ng cm^?2 using collimators of 6 and 8 mm diameter under excitation conditions of 50 kV, 35 mA. The accuracy of the measurements was checked using IAEA SOIL‐7 and NIST 3087a Certified Reference Materials. The experimental values differed by <5% from the certified values. The total reflection x‐ray fluorescence (TXRF) facility added as a module to the existing XRF system provides detection limits between 0.1 and 100 pg for most of the elements measured. Copyright © 2005 John Wiley & Sons, Ltd.     

Quantitative or semi‐quantitative?–laboratory‐based WD‐XRF versus portable ED‐XRF spectrometer: results obtained from measurements on nickel‐base alloys

‘Semi‐quantitative’ analytical procedures are becoming more and more popular. Using such procedures, the question of the accuracy of results arises. The accuracy of an analytical procedure depends to a great extent on spectral resolution, counting statistics and matrix correction. Two ‘semi‐quantitative’ procedures are compared with a quantitative analytical program. Using a laboratory‐based wavelength‐dispersive x‐ray fluorescence (WD‐XRF) spectrometer and a portable energy‐dispersive x‐ray fluorescence (ED‐XRF) spectrometer, 28 different nickel‐base alloy Certified Reference Materials (CRMs) were analyzed. Line interferences and inaccurate matrix correction are reasons for deviations from the reference value. As the comparison shows, ‘semi‐quantitative’ analyses on the WD‐XRF spectrometer can be accepted as quantitative determinations. The investigations show that the results obtained with the portable ED‐XRF spectrometer do not meet the quality requirements of laboratory analysis, but they are good enough for field investigations. Copyright © 2004 John Wiley & Sons, Ltd.     

Analytical Study of Raw Materials of Zinc Oxide Used for Enamels on Industrial Ceramics: Quantitative Analysis of Zinc,Lead, and Sulfur in These Samples by X‐ray Fluorescence and Flame Atomic Absorption Spectrometry

An analytical study is carried out to optimize X‐ray fluorescence (XRF) and flame atomic absorption spectrometry (FAAS) quantitative analysis of Zn, Pb, and S in ZnO samples commonly used to obtain industrial ceramic enamels. Pb and S in the raw materials often contaminate ZnO and are very detrimental in industrial applications. Thus, very accurate analytical determination of these elements in ceramic samples is extremely important. First of all, a mineralogical study by X‐ray diffraction (XRD) on the different components in these raw materials and the materials produced during the firing process is performed in order to establish the mineral forms in a reference sample for analysis by XRF spectrometry. The working conditions are optimized for XRF multielemental analysis, using the sample in the form of pellets, due to high loss on ignition (LOI) values. The preparation of suitable standards and working conditions for FAAS analysis have also been optimized. The content of these elements was determined by FAAS for the reference sample and several samples for industrial use, and the results were compared with those obtained by XRF. Comparison of the results obtained from XRF and FAAS analysis of Pb and Zn show more accurate values for FAAS. For ZnO, an accuracy of 0.11% with ±0.1% precision by FAAS and 0.46% accuracy with ±0.2% precision by XRF are found. For PbO, 1.06% accuracy and ±0.06% precision using FAAS and 5.6% accuracy and ±0.35% precision by XRF were found. For SO₃ determined only by XRF, accuracy was 4.76% with ±0.25% precision. These values are highly satisfactory given that these two elements are only found in small proportions.     

Determination of Mg and Ti in Ziegler–Natta catalysts by x‐ray fluorescence spectrometry

The metal content in Ziegler–Natta catalysts based on Ti and Mg derivatives could not be determined directly by x‐ray fluorescence (XRF) spectrometry owing to the instability of the catalyst. The samples were then calcined and the resultant Mg and Ti oxides were characterized by x‐ray diffraction (XRD). A series of synthetic standards were prepared with high‐purity MgO and TiO₂, since there were no available certified standards for the catalysts. Samples and standards were compressed with high‐purity H₃BO₃ flux. This protocol was shown to be reproducible, having a correlation coefficient of 0.9999. The metal contents determined by XRF were in accordance with those obtained by a complexometric titration (Mg) and a UV–visible spectrophotometric method (Ti). Copyright © 2004 John Wiley & Sons, Ltd.     

The Planck Constant for the Definition and Realization of the Kilogram

On May 20, 2019 the values of the Planck, h, and Avogadro, N_A, constants will be fixed, revising our measurement system, the International System of Units (SI), and providing a new way to get mass traceability. While the famous energy relations mc² and hf may remind many that the Planck constant is indeed related to mass, it is less recognized how this is also true for the Avogadro constant. These concepts are reviewed in the context of the upcoming revision of the SI. How the fixed values were chosen and how mass traceability will be maintained with the smallest uncertainty are also discussed.     

Preparation of sulfur reference materials that reproduce atmospheric particulate matter sample characteristics for XRF calibration

Energy‐dispersive X‐ray fluorescence (XRF) is an important tool used in routine elemental analysis of atmospheric particulate matter (PM) samples collected on polytetrafluoroethylene (PTFE) membrane filters. The method requires calibration against thin‐film standards of known elemental masses commonly obtained from commercial suppliers. These standards serve as a convenient and widely accepted interlaboratory reference but can differ significantly from samples in their chemical composition, substrate, and geometry. These differences can introduce uncertainties regarding the absolute accuracy of the calibration for atmospheric samples. Continuous elemental records of the US Interagency Monitoring of Protected Visual Environments (IMPROVE) PM monitoring network extend back to 1988. Evaluation of long‐term concentration trends and comparison with other networks demand a calibration that is accurate and precise compared with the uncertainty of the XRF measurement itself. We describe a method to prepare sulfur reference materials that are optimized for calibration of XRF instruments used to analyze IMPROVE PM samples. The reference materials are prepared by using the atmospheric form of the element, by reproducing the sample geometry, and by using the same substrate as in samples. Our results show that stable, pure, anhydrous, and stoichiometric deposits are collected onto the filter substrates, and furthermore, that the reference material masses are accurate and have acceptable uncertainty in the measurement range. The XRF response of the sulfur reference materials is similar to other commercial standards and is linear in the measurement range, and the slope of the multipoint calibration curve has very low uncertainty. These reference materials are valid for the calibration of XRF systems, and they bring improved transparency and credibility to the IMPROVE calibration. Copyright © 2013 John Wiley & Sons, Ltd.     

X射线荧光分析钒钛铁矿中主次量元素

四硼酸锂为熔剂 ,硝酸锂为氧化剂防止硫元素挥发损失 ,溴化锂作脱模剂 ,玻璃熔片法制备样品。干扰曲线法结合理论α系数法对谱线重叠干扰和基体效应进行校正 ,建立了 XRF测定钒钛铁矿中 Mg,Al,Si,P,S,Ca,Ti,V,Mn,TFe等主次量元素的分析方法。该方法经标准样品验证 ,与推荐值符合较好。 10次制样测量各组分 RSD在 0 .2 7%— 5 .2 4 %范围内     

Monte Carlo simulation code for confocal 3D micro‐beam X‐ray fluorescence analysis of stratified materials

Stratified materials are of great importance for many branches of modern industry, e.g. electronics or optics and for biomedical applications. Examination of chemical composition of individual layers and determination of their thickness helps to get information on their properties and function. A confocal 3D micro X‐ray fluorescence (3D µXRF) spectroscopy is an analytical method giving the possibility to investigate 3D distribution of chemical elements in a sample with spatial resolution in the micrometer regime in a non‐destructive way. Thin foils of Ti, Cu and Au, a bulk sample of Cu and a three‐layered sandwich sample, made of two thin Fe/Ni alloy foils, separated by polypropylene, were used as test samples. A Monte Carlo (MC) simulation code for the determination of elemental concentrations and thickness of individual layers in stratified materials with the use of confocal 3D µXRF spectroscopy was developed. The X‐ray intensity profiles versus the depth below surface, obtained from 3D µXRF experiments, MC simulation and an analytical approach were compared. Correlation coefficients between experimental versus simulated, and experimental versus analytical model X‐ray profiles were calculated. The correlation coefficients were comparable for both methods and exceeded 99%. The experimental X‐ray intensity profiles were deconvoluted with iterative MC simulation and by using analytical expression. The MC method produced slightly more accurate elemental concentrations and thickness of successive layers as compared to the results of the analytical approach. This MC code is a robust tool for simulation of scanning confocal 3D µXRF experiments on stratified materials and for quantitative interpretation of experimental results. Copyright © 2011 John Wiley & Sons, Ltd.     

The determination of elements in welding fume by X‐ray spectrometry and UniQuant

Welding is a hazardous process with an associated risk of health effects related to the fume arising from the core metal, flux components and welding surface. X‐ray fluorescence (XRF) is commonly used to determine elemental concentrations as part of occupational hygiene investigations using conventional calibrations. A method is proposed to determine elements in welding fume using XRF and a fundamental parameter software package known as UniQuant^®. This was found to remove the need for special dust standards being prepared as the calibration used was based on a series of standards supplied with UniQuant that would cover all sample types. A conventional calibration and UniQuant calibration were set up and elements found in welding fume were determined from tin to titanium. Samples obtained from the Health and Safety Laboratory Workplace Analysis Scheme for Proficiency (WASP) programme were also analysed by both methods for nickel, iron, manganese and chromium. For the normal calibration, average recovery results for the WASP samples were between 92 and 103% of the target value with relative standard deviations of 3‐7%. For the UniQuant calibration, average recovery results for the WASP samples were between 97 and 112% of the target value with relative standard deviations of 3‐10%. These results are well within analytical performance expectations for the type of welding fume matrix analysed. The method was applied to real welding fume samples collected from workplaces. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation of arsenic‐containing white rice grains as calibration standards for X‐ray fluorescence analysis of total arsenic in cereals

A preparation method of arsenic‐containing white rice grains as calibration standards was developed for the X‐ray fluorescence (XRF) analysis of arsenic in rice grains. Calibration standards were prepared by adding 10 g of white rice grains (from Japan) to 100 ml methanol‐containing dimethylarsinic acid corresponding to 2–100 µg arsenic. The mixture was heated, dried at 150 °C, cooled to room temperature, and then stored in a silica gel desiccator. A total of 5.0 g of each calibration standard was packed into a polyethylene cup (32 mm internal diameter and 23 mm height) covered with a 6‐µm‐thick polypropylene film and then analyzed by wavelength‐dispersive XRF spectrometry. The calibration curve for arsenic obtained from the white rice grains containing arsenic showed good linearity over a concentration range of 0.21–5.00 mg kg^?1 arsenic. The limit of detection of arsenic was 0.080 mg kg^?1. To check the reliability of the XRF method, the concentrations of arsenic in six samples of grain cereals and two samples of flour were compared with those obtained by atomic absorption spectrometry after acid decomposition. The values obtained by both analytical methods showed good agreement. Copyright © 2016 John Wiley & Sons, Ltd.     

Approaches to solid sample preparation based on analytical depth for reliable X‐ray fluorescence analysis

In this paper, we discuss approaches to prepare solid samples for X‐ray fluorescence spectrometry (XRF). Although XRF can be used to analyze major and minor elements in various solid samples including powders and grains without dissolution techniques, to obtain reliable XRF results, the prepared sample must meet certain criteria related to homogeneity, particle size, flatness, and thickness. The conditions are defined by the analytical depth of fluorescent X‐rays from analytes, and the analytical depth can be estimated from the X‐ray absorption related to the energy of each X‐ray and the composition and density of the sample. For example, when the sample flatness and particle size are less than the analytical depth and the sample possesses homogeneity within a depth less than the analytical depth, the XRF results are representative of the entire sample. Furthermore, an appropriate sample thickness that is larger than the analytical depth or constant can prevent changes in fluorescent X‐ray intensity with variations in sample thickness. To obtain accurate and reproducible measurements, inhomogeneous solid samples must be pulverized, homogenized, and prepared as loose powder, powder pellets, or glass beads. This paper explains the approaches used to prepare solid samples for XRF analysis based on the analytical depths of fluorescent X‐rays. Copyright © 2016 John Wiley & Sons, Ltd.     

熔融制样X射线荧光光谱法测定锰铁合金中硅、锰和磷含量

用熔融后的四硼酸锂制作铂金坩埚保护层,以Ba02做氧化剂,在马弗炉内通过逐渐升温来氧化锰铁合金,然后熔融制取玻璃熔片,用X射线荧光(XRF)光谱分析锰铁中硅、锰和磷含量.本法有效消除了锰铁合金熔融制样过程中的坩埚腐蚀问题,分析误差可完全控制在国家相关标准允许的偏差内,实现了锰铁合金各元素的快速准确测定.     

A risk assessment study of heavy metals in ambient air by WD‐XRF spectrometry using aerosol‐generated filter standards

A risk assessment study of the air quality in the surrounding of roads covered with slags coming from the non‐ferrous metal industry was performed. A monitoring campaign was carried out at three locations in Flanders by collecting the PM10 fraction and the total suspended particulates (TSP) of the airborne dust particles, entrapping heavy metals, on membrane filters. The heavy metal concentration on the dust filters was determined by wavelength‐dispersive x‐ray fluorescence (WD‐XRF) spectrometry. The XRF calibration curves were set up with filter standards prepared in the laboratory using an aerosol‐generated loading system. The acquired WD‐XRF results were confirmed by inductively coupled plasma atomic emission spectrometric (ICP‐AES) measurements after acid digestion on a selected number of filters. Electron probe microanalysis (EPMA) confirmed that aerosol‐loaded filter standards and dust filters with a concentration level of the analyzed element below 3300 ng cm^?2 were homogeneously distributed. Dust filters with higher concentrations, and especially filters loaded with the TSP fraction, reflected an inhomogeneous distribution of the analyzed element on the filter. The WD‐XRF analytical results acquired in the monitoring campaign revealed that the concentration of Pb on the dust filters never exceeded the immission standard (yearly average) of 2000 ng m^?3. It can be stated that the impact on human health is limited and can still be reduced by covering the polluted roads with a layer of asphalt. Further evaluation of soil and water samples from the nearby surroundings reveals that the heavy metal content in the slags makes an important contribution to environmental pollution, especially the contamination of groundwater. Copyright © 2003 John Wiley & Sons, Ltd.     

Determination of Trace Elements in High‐Purity Palladium by Inductively Coupled Plasma Mass Spectrometry Using an Internal Standard Method

Method validation of inductively coupled plasma mass spectrometry analyses for trace impurities in high‐purity materials is often limited not only by the lack of suitable reference materials with the same matrix composition but also by the lack of a significant number of certified trace element concentrations in the available reference materials. This paper demonstrates a new and simple method for the direct determination of 44 trace elements in high‐purity palladium using inductively coupled plasma mass spectrometry and an internal standard method. Sc and In were employed as internal standards to effectively eliminate nonspectral interferences from the Pd matrix. The detection limits of the 44 trace impurities were from 0.00078 to 0.46 µg/mL and the relative standard deviations (n=6) were below 3.5%. The method was further validated using a palladium standard material (Aldrich palladium standard material, CAS no. 7440053). The analytical results are in good agreement with the certified values.     

Monitoring the polyamide 11 degradation by thermal properties and X‐ray fluorescence spectrometry allied to chemometric methods

The influence of temperature (110 and 120 °C) on the ageing of piping made from polyamide 11 (PA‐11) containing 10–12% of plasticizer was studied using deionized water (pH ≈ 7.0). A clean analytical methodology has been employed for quality control of polymeric materials: energy‐dispersive X‐ray fluorescence spectrometry (ED‐XRF). It provides a fast and suitable technique to characterize chemical elements because of its multielemental capability, good sensitivity, high precision, short analytical time, and nondestructive nature. Herein, the content of additive in PA‐11 was monitored from ED‐XRF measurements where the abundance of the S line is directly related to the ageing time, agreeing with the thermogravimetric analysis. The XRF data were allied to chemometric treatment to classify PA‐11 samples according to the amount of additive and weight average molar mass change, predicting the ageing time, and viscosity values of PA‐11. Therefore, the XRF can be used as a clean analytical methodology to monitor the PA‐11 degradation, thus eliminating the use of toxic organic solvents (necessary to viscosity measurements) and reducing the working time. Also, the effect of hydrolysis on the structure over time and the material morphology were monitored through measurements of dynamic mechanical analysis and differential scanning calorimetry. Copyright © 2012 John Wiley & Sons, Ltd.     

Application for optical thermometers calibration based on virtual instruments

In this paper we present a new developed application for calibration of optical thermometers which is implemented in the Serbian Metrology Institute. The method for calibration of optical thermometer–pyrometer is based on measuring blackbody temperature via thermocouple standards and measuring voltage on pyrometer in temperature range from 550 to 1650 °C. The objective is to precisely determinate calibration curve of pyrometer—transfer function. The metrology traceability was realized through thermocouples standard which has traceability to the international standard. A developed application has a role to control and supervise calibration process. Based on virtual instruments (VI), application offers monitoring measurement parameters in real time on three charts. The main advantage of the developed VI application is reduction of measurement uncertainty of type A by increased accuracy with multi—temperature measurement up to 3 thermocouples on temperature equilibrium in the measurement system and automatic data processing by converting voltage to temperature, calculating the mean value and standard deviation of the mean value. Advantage is also reflected in permanent data logging while application is running and low cost and user friendly interface One of the goals is to improve quality of metrological services through this application and support the establishment of a traceability chain to SI.     

Nanometer Calibration Particles: What is Available and What is Needed?

Information on available polystyrene calibration spheres is presented regarding the particle diameter, uncertainty in the size, and the width of the size distribution for particles in a size range between 20 and 100nm. The use of differential mobility analysis for measuring the single primary calibration standard in this size range, 100nm NIST Standard Reference Material®1963, is described along with the key factors in the uncertainty assessment. The issues of differences between international standards and traceability to the NIST Standard are presented. The lack of suitable polystyrene spheres in the 20–40nm size range will be discussed in terms of measurement uncertainty and width of the size distributions. Results on characterizing a new class of molecular particles known as dendrimers will be described and the possibilities of using these as size calibration standards for the size range from 3 to 15nm will be discussed.