水中柴油浓度峰值法与积分荧光测量模型性能比较

针对浓度荧光测量时峰值法和积分法的选择问题,在理论和实验两方面对两种方法进行比较。首先理论分析峰值法和积分法的浓度测量原理;其次利用FS920型稳态荧光光谱仪扫描纯水、柴油与其混合液样品的三维荧光光谱,根据最强荧光峰确定样品的最佳激发波长为290 nm;再次根据最佳激发波长扫描浓度较低的5种样品的二维荧光光谱,由平均光谱确定主峰和肩峰波长分别为360 nm和326 nm;然后分析比较主峰和肩峰中心扩展区间和区域内积分荧光法校正模型参数的变化规律;最后,通过留一法交叉验证7种不同方法所建浓度校正模型的精度并进行比较。实验结果表明:在低浓度下,峰值和积分荧光强度与浓度之间都具有良好的线性关系,相关系数r0.99,与理论相符;相关系数和校正决定系数随积分范围的增大先增大后减小,在峰值附近2~10 nm范围内存在极值;就积分荧光浓度模型本身而言,主峰优于肩峰,模型灵敏度、模型误差与残差平方和随积分范围的增大而增大;在浓度配置误差范围内,峰值法和积分法浓度测量绝对误差的平均值均在0.002‰以内。     

差分拉曼光谱结合XRF对塑料药瓶的多元分类研究

目的 构建一种药瓶的分类及预测模型。方法 利用差分拉曼光谱和X射线荧光光谱对54个不同品牌和产地的塑料药瓶进行分析检验。结果 得到了54个样品的差分拉曼谱图及Cl、Ca、Ti、Fe、Zn等元素的含量。利用主成分分析对差分拉曼光谱数据进行降维,再利用系统聚类将降维后的数据分为8类,并以此为依据建立判别分析模型,最终判别模型经交叉验证可知准确率达到90.7%,多层感知器的分类准确率为100%,分类效果较好。结论 差分拉曼光谱可以根据谱图中的特征峰推断样品的分子结构,并且可以根据峰位对样品进行分类,并建立分析模型,X射线荧光光谱可以通过各元素的种类和含量的不同对样品进行区分,实现组内的细化。差分拉曼光谱和X射线荧光光谱可以分别从有机和无机的角度对药瓶进行分类,在分析上可以优势互补,可为公安机关实际办案探索出一种新的光谱联用角度和方法。     

定性半定量分析软件IQ在X射线荧光光谱方法中的应用研究

本文介绍了X射线荧光光谱定性半定量分析方法以及定性半定量分析软件IQ+的产生和发展。通过对化学、材料、机械、土建、微电子、物构及工艺制造等专业的一些样品的实例分析,展示了X射线荧光光谱定性半定量分析方法在科学研究中的广泛应用。     

浸渍法在玻璃单层上选择沉积TiO2薄膜

以硅烷偶联剂作为表面修饰剂,在大气气氛中于普通载玻片上的有机单层上选择沉积制备出TiO2薄膜.使用差示扫描量热-失重(DSC-TG)分析、X射线衍射(XRD)分别对TiO2薄膜的凝胶前驱体和TiO2粉末进行表征,并对TiO2薄膜进行了X射线荧光光谱(XRF)分析.结果表明,所制备的TiO2薄膜是纳米级的锐钛矿单层膜.     

多技术联用鉴别含铅固体废物

采用X射线荧光光谱、X射线衍射等技术,结合超景深显微镜、扫描电镜等设备,对某含铅样品进行化学成分、物相组成和微观形貌分析,判断是否为固体废物.结果表明:样品主成分为Pb3(CO3)2(OH)2,PbSO4和Na2SO4等,并且含有大量玻璃态的钠钙铝硅酸盐和呈球状、椭球状、串珠状的金属铅和铅铁氧化物.样品中的硫酸铅呈疏松...     

X射线荧光测定饮料中的Ca,Mg,Fe和Zn

将５０μｌ饮料试液滴在滤纸上制成薄样，用Ｘ射线荧光测定其中的钙、镁、铁和锌。用数学校正法校正饮料试液与标准样品间的基体差异后，分析结果与经消化处理后的原子吸收测定值基本一致。并就取样体积和样品的保存等问题进行了探讨。     

土壤物证鉴定中的微观测试与表征技术

在司法物证检验鉴定中,为了鉴别2种未知土壤物证的来源性问题,采用X射线荧光光谱、X射线衍射和激光粒度分析,对样品进行测试和对比。结果表明,2种样品在化学组成、矿物组成和粒径特征方面均存在较大差异,二者虽然当时取自同一案发现场,但是它们之前的来源是不同的。     

EDX-LE型X射线能谱仪测试银饰品含量的条件设置

利用能量色散型X射线荧光光谱仪(XRF)测试贵金属首饰含量,测试结果受选择的测试条件、样品成分、样品形状特征等因素的影响。通过日本岛津公司的EDX-LE型能量色散型X射线荧光光谱仪测试银首饰中的银含量,分析得出样品测试面是否平整、准直器的大小是影响实验测试值准确性的最主要因素,测试时需要选择较大的准直器、选择平整的测试面且多次测量以得出测试结论。     

光谱预处理对棉涤混纺面料近红外定量模型的影响

以46个棉涤混纺面料样品为研究对象,采集样品的近红外漫反射光谱,光谱范围为12 000~4 000 cm-1,利用偏最小二乘法建立定量校正模型,并用交叉检验法对模型进行检验,以交叉验证均方差RMSECV和决定系数R2作为判断模型优劣的标准.对利用无光谱预处理、一阶导数法、二阶导数法、多元散射校正和矢量归一化五种不同预处理方法所建的模型进行了比较,发现对光谱进行矢量归一化预处理所建模型最优;此外还分析了建立纺织布料的近红外光谱定量分析模型时主要的误差来源及近红外光谱分析技术用于纺织面料定量分析的可行性.     

22K金内部标准样品的研制

X射线荧光光谱分析法因其检测速度快,无须破坏样品等优点,被广泛的应用于各行各业中,同样在贵金属含量分析中占有举足轻重的地位。但是,荧光光谱分析法也有其自身的缺点,为了保证结果的准确性在检测时必须要使用标样来校正标准曲线,并非所有的标样都能在市面上购买,自制标样便是很多实验室解决困扰的途径之一,定值是否准确将是判断标样好坏最重要的参数,本文介绍一系列的方法来探讨标样的定值。     

Wavelength dispersive X-ray fluorescence imaging

A new wavelength-dispersive X-ray fluorescence (WD-XRF) imaging spectrometer equipped with a two-dimensional X-ray detector was developed in the laboratory. Straight polycapillary optics was applied instead of a soller slit, which is used in conventional WD-XRF spectrometers. X-rays were guided through the straight polycapillary to the exit of the optics by X-ray external total reflections. X-ray fluorescence was dispersed by an analyzing crystal (LiF(200)), keeping the information of elemental distribution on the surface of the sample. The energy resolution of the developed spectrometer was 130-152 eV at the Zn Kα peak. X-ray elemental images of Cu Kα and Ni Kα were successfully obtained by an X-ray CCD detector at the corresponding diffraction angles. The analytical performance of this technique, and further improvements are discussed.     

Analysis of mosses along Sarp-Samsun highway in Turkey

The elemental analysis of mosses along Sarp-Samsun highway in Turkey was determined using energy dispersive X-ray fluorescence method. A radioisotope excited X-ray fluorescence analysis using the method of multiple standard additions is applied for the elemental analysis of mosses. An annular 50 mCi (241)Am radioactive source and annular 50 mCi (55)Fe radioactive source were used for excitation of characteristic K X-rays. An Si(Li) detector which has a 147 eV full width at half maximum for 5.9 keV photons was used for intensity measurements. A qualitative analysis of spectral peaks showed that the samples contained phosphates, potassium, calcium, titanium, iron, strontium, tin and barium. Since this study is the elemental analysis along the highway, one can expect to detect Pb. Due to the detection limit of EDXRF, elements were analyzed with Atomic Absorption Spectroscopy (AAS) for Pb. Evaluation of these elements with their potential hazards for ecology and human is briefly discussed.     

High-definition X-ray fluorescence elemental mapping of paintings

A historical self-portrait painted by Sir Arthur Streeton (1867-1943) has been studied with fast-scanning X-ray fluorescence microscopy using synchrotron radiation. One of the technique's unique strengths is the ability to reveal metal distributions in the pigments of underlying brushstrokes, thus providing information critical to the interpretation of a painting. We have applied the nondestructive technique with the event-mode Maia X-ray detector, which has the capability to record elemental maps at megapixels per hour with the full X-ray fluorescence spectrum collected per pixel. The painting poses a difficult challenge to conventional X-ray analysis, because it was completely obscured with heavy brushstrokes of highly X-ray absorptive lead white paint (2PbCO(3)·Pb(OH)(2)) by the artist, making it an excellent candidate for the application of the synchrotron-based technique. The 25 megapixel elemental maps were successfully observed through the lead white paint across the 200 × 300 mm(2) scan area. The sweeping brushstrokes of the lead white overpaint contributed significant detrimental structure to the elemental maps. A corrective procedure was devised to enhance the visualization of the elemental maps by using the elastic X-ray scatter as a proxy for the lead white overpaint. We foresee the technique applied to the most demanding of culturally significant artworks where conventional analytical methods are inadequate.     

Element-specific detection in capillary electrophoresis using X-ray fluorescence spectroscopy

X-ray fluorescence spectroscopy is demonstrated here as a novel, element-specific detector for capillary electrophoresis. Monochromatic 10 keV X-rays from a synchrotron light source are used to excite core electrons, causing emission of characteristic Kalpha X-ray fluorescence (XRF) lines. Using this technique, XRF energies provide elemental identification, while XRF intensities can be used to quantitate the metal composition of each eluent. An X-ray transparent polymer coupling is used to create a window for the on-line, X-ray detection. This coupling contributes no measurable extra-column variance, and electrophoretic mobilities for the metal complexes used as model solutes are highly reproducible. The combination of XRF detection with capillary electrophoresis (CE-XRF) creates the first on-line detection system that is element-specific, nondestructive, and directly applicable to a broad range of applications including nonelectroactive species. CE-XRF is successfully demonstrated here for high binding-constant complexes of Fe(III), Co(II), Cu(II), and Zn(II). Within a single injection, electropherograms are obtained for each element of interest, with the element identity obtained directly from the emission energy. In contrast with ICPMS, this detection technique is directly on-line and does not require volatilization of the eluent. As a result, element-specific detection is not limited by the sample or the buffer volatility or atomization efficiency. Simultaneous XRF and UV absorbance detection can be used to provide an on-line determination of metal/chelate ratios. Although XRF detection limits are presently only in the 0.1 mM (0.5 ng) range, both collection geometry and incident intensity have yet to be optimized. Further optimization is expected to enhance this detection limit by another 2-3 orders of magnitude. As a result, the advent of XRF detection combined with the separating power of CE presents new possibilities for on-line, element-specific analysis.     

Capillary electrophoresis micro X-ray fluorescence: a tool for benchtop elemental analysis

A new tool was developed for separation and elemental detection by interfacing a simple capillary electrophoresis (CE) apparatus, constructed using a thin-walled fused-silica capillary, with a benchtop energy-dispersive micro X-ray fluorescence (MXRF) system. X-ray excitation and detection of the separated analytes was done using an EDAX Eagle II micro X-ray fluorescence system equipped with a polycapillary Rh target excitation source and a SiLi detector. It was demonstrated that this prototype system could be used for the separation and detection of species containing two different metals from one another, specifically Cu and Co. Free Co could also be separated from Co bound to cyanocobalamin (vitamin B-12). Two organic compounds were also separated from one another, a large biological protein, ferritin, from a small biological organic, cyanocobalamin. Preliminary average detection limits obtained on this system were on the order of 10(-)(4) M and compared favorably to those reported for the similar technique of CE-synchrotron XRF. CEMXRF allows for nondestructive, simultaneous, on-line, benchtop elemental analysis for chemical speciation applications.     

Elemental and molecular characterization of aged polydimethylsiloxane foams

The application and integration of micro X-ray fluorescence (MXRF) and Fourier transform infrared (FT-IR) imaging to polydimethylsiloxane (PDMS) foam aging issues have been applied to cross-sectional images. Previous work has shown the tin in the stannous 2-ethylhexanoate catalyst to be highly mobile and it typically migrates to the PDMS foam upper surface. The current paper discusses a method for the integration of full spectral MXRF and FT-IR imaging of aged foams. Solvent extractions have also been performed on both fresh and aged foams to further examine aged foam properties. Combining elemental and molecular imaging techniques and applying them to PDMS aging provides synergistic information that aids in understanding the sample composition and distribution of components. Application of chemometric analysis to the full spectral elemental and molecular maps demonstrates correlations within the foams of the residual tin, organo-tin functional group moieties, and the presence of nitroplasticizer from an exogenous source.     

Development of microwave-assisted drying methods for sample preparation for dried spot micro-X-ray fluorescence analysis

Although dried spot micro X-ray fluorescence (MXRF) is an effective analytical technique for trace elemental analysis, the sample preparation procedures currently used suffer from a number of drawbacks. These drawbacks include relatively long preparation times, lack of control of the sample preparation environment, and possibility of loss of volatile analytes during the drying process. Microwave-assisted drying offers several advantages for dried spot preparation, including control of the environment and minimized volatility because of the differences between microwave heating and conventional heating. A microwave-assisted drying technique has been evaluated for use in preparing dried spots for trace analysis. Two apparatus designs for microwave drying were constructed and tested using multielement standard solutions, a standard reference material, and a "real-world" semiconductor cleaning solution. Following microwave-assisted drying of these aqueous samples, the residues were redissolved and analyzed by ICPMS. Effective recovery was obtained using the microwave drying methods, demonstrating that the microwave drying apparatus and methods described here may be more efficient alternatives for dried spot sample preparation.     

Simultaneous soft X-ray transmission and emission microscopy

Novel low-energy X-ray fluorescence (LEXRF) system based on a multiple Si drift detector (SDD) configuration has been developed and implemented in the European TwinMic X-ray microspectroscopy station operating at the Italian synchrotron radiation facility ELETTRA. The setup, hosting up to eight large-area SDDs with specially adapted readout electronics, has demonstrated excellent performance for elemental analysis in the 280–2200 eV photon energy range, which covers the K and L edges of light elements, starting from C. The great advantage is the simultaneous acquisition of LEXRF, absorption and phase contrast maps, providing complementary information on elemental composition and morphology of specimen at submicrometer length scales.     

Compact pnCCD-based X-ray camera with high spatial and energy resolution: a color X-ray camera

For many applications there is a requirement for nondestructive analytical investigation of the elemental distribution in a sample. With the improvement of X-ray optics and spectroscopic X-ray imagers, full field X-ray fluorescence (FF-XRF) methods are feasible. A new device for high-resolution X-ray imaging, an energy and spatial resolving X-ray camera, is presented. The basic idea behind this so-called "color X-ray camera" (CXC) is to combine an energy dispersive array detector for X-rays, in this case a pnCCD, with polycapillary optics. Imaging is achieved using multiframe recording of the energy and the point of impact of single photons. The camera was tested using a laboratory 30 μm microfocus X-ray tube and synchrotron radiation from BESSY II at the BAMline facility. These experiments demonstrate the suitability of the camera for X-ray fluorescence analytics. The camera simultaneously records 69,696 spectra with an energy resolution of 152 eV for manganese K(α) with a spatial resolution of 50 μm over an imaging area of 12.7 × 12.7 mm(2). It is sensitive to photons in the energy region between 3 and 40 keV, limited by a 50 μm beryllium window, and the sensitive thickness of 450 μm of the chip. Online preview of the sample is possible as the software updates the sums of the counts for certain energy channel ranges during the measurement and displays 2-D false-color maps as well as spectra of selected regions. The complete data cube of 264 × 264 spectra is saved for further qualitative and quantitative processing.     

Application of conventional and microbeam synchrotron radiation x-ray fluorescence and absorption for the characterization of human nails

The synchrotron radiation based spectroscopies X-ray fluorescence and X-ray absorption fine structure are used to detect illness-related changes in the elemental distribution and bonding environment of metals in human nails. The effective atomic number of a collection of nails is determined using two methods, the X-ray transmittance and the scattering method, and is found equal to 7.5 +/- 0.5. X-ray fluorescence maps of the elemental distributions, recorded with a lateral resolution of 5 microm, reveal that S, Ca and Zn are distributed homogeneously while Fe tends to cluster. In the Fe-rich clusters, which have a diameter in the range 15-30 microm, the Fe concentration is 10 times higher than in the matrix. The Zn K edge X-ray Absorption Fine Structure spectra reveal that Zn, in the nails from healthy donors and patients suffering from lung diseases, is four-fold coordinated with N and S and the Zn-N and Zn-S distances are equal to 2.03 A and 2.25 A, respectively. Finally the signature of various bonds in the C-, O- and N- K near edge X-ray absorption fine structure spectra is discussed.