Quantitative analysis by energy dispersive X-ray fluorescence by the transmission method applied to geological samples

Abstract

Three certified samples of different matrices (Soil-5, SL-1/IAEA and SARM-4/SABS) were quantitatively analysed by energy dispersive X-ray fluorescence with radioisotopic excitation. The observed errors were about 10-20% for the majority of the elements and less than 10% for Fe and Zn in the Soil-5, Mn in SL-1, and Ti, Fe and Zn in SARM-4 samples. Annular radioactive sources of Fe-55 and Cd-109 were utilized for the excitation of elements while a Si(Li) semiconductor detector coupled to a multichannel emulation card inserted in a microcomputer was used for the detection of the characteristic X-rays. The fundamental parameters method was used for the determination of elemental sensitivities and the irradiator or transmission method for the correction of the absorption effect of characteristic X-rays of elements on the range of atomic number 22 to 42 (Ti to Mo) and excitation with Cd-109. For elements in the range of atomic number 13 to 23 (Al to V) the irradiator method cannot be applied since samples are not transparent for the incident and emergent X-rays. In order to perform the absorption correction for this range of atomic number excited with Fe-55 source, another method was developed based on the experimental value of the absorption coefficients, associated with absorption edges of the elements. Key words: quantitative analysis, X-ray fluorescence, geological samples, energy dispersive. ANÁLISE QUANTITATIVA POR FLUORESCÊNCIA DE RAIOS X COM DISPERSÃO POR ENERGIA PELO MÉTODO DA TRANSMISSÃO APLICADA À AMOSTRAS GEOLÓGICASRESUMO: Foi realizada a análise quantitativa de três amostras certificadas de diferentes matrizes (Soil-5/IAEA, SL-1/IAEA e SARM-4/SABS) através da fluorescência de raios X por dispersão de energia e excitação radioisotópica. Os erros observados foram em torno de 10 a 20% para a maioria dos elementos e inferiores a 10% para Fe e Zn na amostra Soil-5, Mn na amostra SL-1 e Ti, Fe e Zn na amostra SARM-4. Para a excitação dos elementos presentes foram empregadas as fontes radioativas anelares de Fe-55 e Cd-109, enquanto que na detecção dos raios X característicos utilizou-se um detector de Si(Li), acoplado a uma placa analisadora de pulsos multicanal, inserida em um microcomputador. O método dos parâmetros fundamentais foi utilizado na determinação da sensibilidade elementar e o método do irradiador ou da transmissão na correção dos efeitos de absorção dos raios X característicos de elementos de número atômico entre 22 e 42 (Ti ao Mo) e excitação com Cd-109. Para elementos na faixa de número atômico entre 13 e 23 (Al ao V), o método do irradiador não pode ser aplicado, pois a amostra não é transparente aos raios X incidentes e emergentes, e um outro método baseado nas medidas experimentais dos coeficientes de absorção com Cd-109, associados aos saltos de absorção e excitação com Fe-55 foi então desenvolvido a fim de se efetuar a correção da absorção para esta faixa de número atômico. Descritores: Análise quantitativa, fluorescência de raios X, amostras geológicas, energia dispersiva.

Application of X‐ray fluorescence spectrometry in plant science: Solutions, threats, and opportunities

“…In particular, high accuracy, precision, versatility, sensitivity, and advanced standard-less calibration strategies make WDXRF an excellent technique for the quick analysis of major, minor, and trace elements. [61][62][63][64][65][66][67][68] In addition, the use of the analyzing crystals such as LiF (200) and PET (002), it is quite easy to detect lighter elements (low Z) more accurately and precisely. Recently, WDXRF spectroscopy has been used to investigate the elemental changes in the nematode-infested roots of papaya plants and okra plants.…”

“…[ 62 ] It is based on the measurement of the X‐ray beam from the test sample alone. [ 63,64 ] It is a very efficient technique for the correction of matrix absorption effects in the XRF analysis of the test samples of intermediate thickness. [ 64 ] Its relative simplicity and versatility are supplemented by good accuracy, particularly in trace element analysis.…”

Simultaneous Spectrophotometric Determination of Aluminum and Iron in Micellar Media by Using the H‐Point Standard Addition Method

“…Several reports have been published on the simultaneous determination of aluminum and iron, including the expensive instrumental technique of x-ray fluorescence with radio isotopic excitation. 2 Chromatographic techniques such as high performance liquid chromatography (HPLC) 3,4 and atomic absorption spectrometry 5,6 have been applied for simultaneous determination of these two ions in a mixture of many ions, although in some cases sensitivity is relatively low and a preconcentration step is needed. Inductively coupled plasma atomic emission spectrometry (ICP-AES), 7 inductively coupled plasma -mass spectrometry (ICP-MS) and ICP-AES, 8 combined on line HPLC and high resolution ICP-MS 9 have been also applied for simultaneous determination of aluminum and iron.…”

Matrix characterization using synchrotron radiation X-ray diffraction

“…Matrix effects in the samples influence the accuracy of EDXRF analysis. If the samples to be analyzed are thick, the matrix absorption is the most determining important factor (Simabuco and Nascimento, 1994;De Jesus et al, 2000;Anjos et al, 2000) in the accuracy of a measurement. In this paper, we propose use of X-ray diffraction (Barroso et al, 1999) as a non-destructive technique combined with EDXRF for multi-elemental analysis.…”