Analysis fluorescence

The working principle of XRF analysis is the measurement of wavelength or energy and intensity of the characteristic photons emitted from the sample. This allows the identification of the elements present in the analyte and the determination of their mass or concentration. AU the information for the analysis is stored in the measured spectrum, which is a line spectrum with all characteristic lines superimposed above a certain fluctuating background. Other interaction processes, mainly the elastic and inelastic scattering of the primary radiation on sample and substrate, induce the background. 

Measurement of the spectrum of the emitted characteristic fluorescence radiation is performed using wavelength-dispersive (WD) and energy-dispersive (ED) 

Handbook of Spectroscopy, Volume 1. Edited by Gunter Gauglitz and Tuan Vo-Dinh Copyright 2003 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-29782-0 

By introducing special excitation geometries, optimized sources and detectors, the picogram and even femtogram range of absolute analyte detection capacity can be reached in terms of concentrations, the same improvement factor can be attained, i. e. from the Lig g towards the pg g level under the best conditions. 

In principle, XRE analysis is a multi-element analytical technique and, in particular, the simultaneous determination of all the detectable elements present in the sample is inherently possible with EDXRE. In WDXRF both sequential and simultaneous detection modes are possible. 

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Schenk, G. Historical Overview of Fluorescence Analysis to 1980, Spectroscopy 1997,12, 47-56. 

For electronically excited species, the emitted light can be used for spectroscopic purposes, as in fluorescence analysis. 

Mineral and Chemical Composition. X-ray diffraction is used to determine the mineral composition of an Mg(OH)2 sample. Induced coupled plasma (icp) spectrophotometry is used to measure the atomic concentrations present in a sample. X-ray fluorescence analysis is another comparative instmmental method of determining chemical composition. 

Spectroscopic methods for the deterrnination of impurities in niobium include the older arc and spark emission procedures (53) along with newer inductively coupled plasma source optical emission methods (54). Some work has been done using inductively coupled mass spectroscopy to determine impurities in niobium (55,56). X-ray fluorescence analysis, a widely used method for niobium analysis, is used for routine work by niobium concentrates producers (57,58). Paying careful attention to matrix effects, precision and accuracy of x-ray fluorescence analyses are at least equal to those of the gravimetric and ion-exchange methods. 

L. Munck, ed.. Fluorescence Analysis in Foods,]ohxi Wiley Sons, Inc., New York, 1989. 

At X-ray fluorescence analysis (XRF) of samples of the limited weight is perspective to prepare for specimens as polymeric films on a basis of methylcellulose [1]. By the example of definition of heavy metals in film specimens have studied dependence of intensity of X-ray radiation from their chemical compound, surface density (P ) and the size (D) particles of the powder introduced to polymer. Have theoretically established, that the basic source of an error of results XRF is dependence of intensity (F) analytical lines of determined elements from a specimen. Thus the best account of variations P provides a method of the internal standard at change P from 2 up to 6 mg/sm the coefficient of variation describing an error of definition Mo, Zn, Cu, Co, Fe and Mn in a method of the direct external standard, reaches 40 %, and at use of a method of the internal standard (an element of comparison Ga) value does not exceed 2,2 %. Experiment within the limits of a casual error (V changes from 2,9 up to 7,4 %) has confirmed theoretical conclusions. 

If the colloidal systems are considered as objects of X-ray fluorescence analysis, some special features are to be mentioned. 

The goal of our investigation was to develop the X-ray fluorescence analysis procedure for the determination of heavy metals in the paint-and-lacquer materials. 

The procedure of determination of metals in the thin layer without elimination of the non-volatile organic components for different paints containing inorganic pigments was developed. Several techniques of sampling from paint-and-lacquer materials for X-ray fluorescence analysis were proposed. For the study of nonhomogenity of metal distribution in the thin layer we used additionally the local method of X-ray fluorescence analysis. 

In this work the results of reseai ch common sorbtion-X-Ray-fluorescence analysis of Pb(II), Cd(II), Zn(II) and Mo(VI) with preconcentration on complexing chemical silica gel modified with mercaptane groups and modified with 8-hydroxyquinoline were described. The conditions and limits of determination of the X-Ray-fluorescence method in the thin lawyers ai e discussion. 

FEASIBILITY TO APPLY THE PROCEDURE OF NONDESTRUCTIVE X-RAY FLUORESCENCE ANALYSIS OF PLANTS FOR MILK POWDER EXAMINATION... 

RESULTS OF STUDYING HOT PRESSING ADAPTABILITY FOR NONDESTRUCTIVE X-RAY FLUORESCENCE ANALYSIS... 

RESULTS OF EVALUATING NONDESTRUCTIVE X-RAY FLUORESCENCE ANALYSIS OF DRIED MILK SAMPLES OF LIMITED MASS... 

MODERN STATE AND PROSPECTS OF THE DEVELOPMENT OF X-RAY FLUORESCENCE ANALYSIS IN RUSSIA... 

X-RAY FLUORESCENCE ANALYSIS OE COAL CONCENTRATES USING QUASI-SOLID SPECIMENS... 

Among other methods the X-ray fluorescence analysis (XRF) has some advanlages, namely rapidily, seleclivily, accuracy and an opporlunily of aulomalion. Accuracy of Ihe analysis is caused by qualily of Ihe specimen oblained from analyzed sample. 

Over the last seventeen year s the Analytical center at our Institute amassed the actual material on the application of XRF method to the quantitative determination of some major (Mg, Al, P, S, Cl, K, Ti, Mn, Fe) and trace (V, Cr, Co, Ni, Zn, Rb, Sr, Y, Zr, Nb, Mo, Ba, La, Ce, Pb, Th, U) element contents [1, 2]. This paper presents the specific features of developed techniques for the determination of 25 element contents in different types of rocks using new Biaiker Pioneer automated spectrometer connected to Intel Pentium IV. The special features of X-ray fluorescence analysis application to the determination of analyzed elements in various types of rocks are presented. The softwai e of this new X-ray spectrometer allows to choose optimal calibration equations and the coefficients for accounting for line overlaps by Equant program and to make a mathematic processing of the calibration ai ray of CRMs measured by the Loader program. 

N.V. Polosmak and V.A. Tmnova. An analysis of Pazyryk hair (X-ray fluorescent analysis using synclirotron radiation) //Archaeology, Ethnology Anthnoropology of Eurasia, 1(17) 2004, p. 73-71. 

Dzubay, T. G., "X-Ray Fluorescence Analysis of Environmental Samples.". Ann Arbor Science Publishers, Ann Arbor, MI, 1977. 

In Total Reflection X-Ray Fluorescence Analysis (TXRF), the sutface of a solid specimen is exposed to an X-ray beam in grazing geometry. The angle of incidence is kept below the critical angle for total reflection, which is determined by the electron density in the specimen surface layer, and is on the order of mrad. With total reflection, only a few nm of the surface layer are penetrated by the X rays, and the surface is excited to emit characteristic X-ray fluorescence radiation. The energy spectrum recorded by the detector contains quantitative information about the elemental composition and, especially, the trace impurity content of the surface, e.g., semiconductor wafers. TXRF requires a specular surface of the specimen with regard to the primary X-ray light. 

X-Ray Fluorescence analysis (XRF) is a well-established instrumental technique for quantitative analysis of the composition of solids. It is basically a bulk evaluation method, its analytical depth being determined by the penetration depth of the impinging X-ray radiation and the escape depth of the characteristic fluorescence quanta. Sensitivities in the ppma range are obtained, and the analysis of the emitted radiation is mosdy performed using crystal spectrometers, i.e., by wavelength-dispersive spectroscopy. XRF is applied to a wide range of materials, among them metals, alloys, minerals, and ceramics. 

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