Random left-censoring: a statistical approach accounting for detection limits in x-ray fluorescence analysis

2004 ◽  
Vol 33 (4) ◽  
pp. 306-311 ◽  
Author(s):  
M. Pajek ◽  
A. Kubala-Kukuś ◽  
D. Banaś ◽  
J. Braziewicz ◽  
U. Majewska
Keyword(s):  
Statistical Approach ◽  
Detection Limits ◽  
Fluorescence Analysis ◽  
X Ray

scholarly journals Analysis of individual microscopic particles by means of synchrotron radiation induced x-ray micro fluorescence

1992 ◽  
Vol 50 (2) ◽  
pp. 1766-1767
Author(s):  
K. Janssens ◽  
F. Adams ◽  
M.L. Rivers ◽  
K.W. Jones
Keyword(s):  
Synchrotron Radiation ◽  
Detection Limits ◽  
Fluorescence Analysis ◽  
Individual Particle ◽  
Quantitative Character ◽  
Particle Analysis ◽  
X Ray ◽  
Interesting Approach ◽  
Radiation Induced ◽  
Backscattered Electron

Micro-SXRF (Synchrotron X-ray Fluorescence) or micro-SRIXE (Synchrotron Radiation Induced X-ray Emission) is a microanalytical technique which combines the sensitivity of more conventional microchemical methods such as Secondary Ion Microscopy (SIMS) and μ-PIXE (Proton Induced X-ray Emission) with the non-destructive and quantitative character of X-ray fluorescence analysis. The detection limits attainable at current SXRF-facilities are situated in the ppm (and in favourable cases the sub-ppm) range. The sensitivity of SRIXE can be used advantageously in individual particle analysis. This type of analysis is used, e.g., for studying sources of athmospheric pollution. Analysis of standard NIST micro-spheres at the NSLS-SRIXE facility yielded minimum detection limits in the 1 to 100 ppm range for particle sizes of around 10 to 30 μm.An interesting approach to individual particle characterisation is by means of electron microprobe analysis (EPMA). By using the backscattered electron signals, in an automated fashion, particles can be easily located on a filter substrate and their size and shape determined.

Txrf-Sources-Samples and Detectors

1995 ◽  
Vol 39 ◽  
pp. 755-766
Author(s):  
P. Wobrauschek ◽  
P. Kregsamer ◽  
W. Ladisich ◽  
R. Riede ◽  
Christina Streli ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Detection Limits ◽  
Fluorescence Analysis ◽  
Total Reflection ◽  
Light Elements ◽  
X Ray

Total reflection x-ray fluorescence analysis (TXRF) has reached a mature state but still improvements are possible in selecting the proper components for TXRF and optimizing them in the best suitable way. Two approaches are presented, the extension of the number of detectable elements after K-shell excitation and the improvement of the detection limits. The results show, that the elements from B to U can be detected by their characteristic K-lines and that detection limits for medium Z elements e.g. Ni in the fg range are achievable. Most of the best results have been measured using synchrotron radiation with spectral modifying devices like multilayer monochromators. Other x-ray sources like a windowless tube with exchangeable anodes of either material Al, Si or Mo were successfully tested for the efficient excitation of light elements.

Ultratrace speciation of nitrogen compounds in aerosols collected on silicon wafer surfaces by means of TXRF-NEXAFS

2004 ◽  
Vol 19 (1) ◽  
pp. 81-86 ◽  
Author(s):  
S. Török ◽  
J. Osán ◽  
B. Beckhoff ◽  
G. Ulm
Keyword(s):  
Silicon Wafer ◽  
Detection Limits ◽  
Fluorescence Analysis ◽  
Nitrogen Compounds ◽  
Undulator Radiation ◽  
X Ray ◽  
Acceptable Accuracy ◽  
Rural Aerosols ◽  
X Ray Absorption ◽  
Wafer Surfaces

Total reflection X-ray fluorescence analysis (TXRF) using monochromatized undulator radiation in the PTB radiometry laboratory at the synchrotron radiation facility BESSY II has been employed to investigate the chemical state of nitrogen compounds in aerosols. The aerosol samples of different size fractions were deposited on silicon wafer surfaces in a May impactor. Using a thin window Si(Li) detector, TXRF detection limits for nitrogen are in the upper fg and lower pg range. Taking advantage of the tunability of monochromatized undulator radiation, the near edge X-ray absorption fine structure (NEXAFS) could be combined with TXRF analysis, allowing for the speciation of the aerosols at the nitrogen K absorption edge. Such low detection limits enable an analysis of aerosol samples taken in 10 min with acceptable accuracy. Applicability of the technique to real aerosol samples has been used to compare nitrogen oxidation state in suburban and rural aerosols

scholarly journals Energy dispersive X-ray fluorescence analysis of ancient potteries from Vellore District Tamilnadu, India with statistical approach

2014 ◽  
Vol 7 (1) ◽  
pp. 44-54 ◽  
Author(s):  
R. Ravisankar ◽  
A. Naseerutheen ◽  
A. Chandrasekaran ◽  
S.N. Bramha ◽  
K.V. Kanagasabapathy ◽  
...  
Keyword(s):  
Statistical Approach ◽  
Fluorescence Analysis ◽  
Energy Dispersive ◽  
X Ray

An X-Ray Micro-Fluorescence Analysis System With Diffraction Capabilities

1985 ◽  
Vol 29 ◽  
pp. 423-426 ◽  
Author(s):  
M. C. Nichols ◽  
R. W. Ryon
Keyword(s):  
Fluorescence Detection ◽  
Detection Limits ◽  
Fluorescence Analysis ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Preliminary Work ◽  
Counting Time ◽  
Analysis System

AbstractA prototype X-ray fluorescence system for chemical and phase microanalysis of materials has been developed and tested. Preliminary work with this system has indicated X-ray fluorescence detection limits on the order of 40 picograms for heavier elements such as gold when using a 100 micron collimator, 400 second counting time and a silver anode operating at 12 Kw. Phase identification by X- ray diffraction can be obtained from the same spot. A proposed design for an improved system providing greater elemental sensitivities and capable of semi-automated operation has been completed.

ASSESSING HYDROTHERMAL ALTERATION INTENSITY IN VOLCANIC-HOSTED MASSIVE SULFIDE SYSTEMS USING PORTABLE X-RAY FLUORESCENCE ANALYSIS OF DRILL CORE: AN EXAMPLE FROM MYRA FALLS, CANADA

2020 ◽  
Vol 115 (2) ◽  
pp. 443-453
Author(s):  
Brian A. McNulty ◽  
Nathan Fox ◽  
J. Bruce Gemmell
Keyword(s):  
Hydrothermal Alteration ◽  
Detection Limits ◽  
Fluorescence Analysis ◽  
Massive Sulfide ◽  
Hydrothermal Systems ◽  
Geochemical Data ◽  
Drill Core ◽  
Sulfide Mineralization ◽  
X Ray

Abstract Current portable X-ray fluorescence (pXRF) technology can rapidly and inexpensively yield concentrations of geologically significant elements, typically with instrument detection limits below several tens of parts per million. Based on conventional XRF whole-rock geochemical data, both the Ishikawa alteration index and the chlorite-carbonate-pyrite index increase with proximity to sulfide mineralization at Myra Falls. However, available pXRF technology is typically unable to detect all the elements required to calculate these alteration indices. As a result, there is a need to utilize the elements that are readily detectable using pXRF and apply these to hydrothermal alteration assessment. We propose that Rb/Sr ratios provide a robust proxy for the Ishikawa alteration index and demonstrate that conventional whole-rock XRF analytical results for Rb and Sr can be reproduced using pXRF analysis from drill core surfaces. At Myra Falls, the Rb/Sr ratios vary from <0.1 for least altered rocks, 0.1 to 0.5 for weakly altered rocks, 0.5 to 1.0 for moderately altered rocks, 1.0 to 2.0 for strongly altered rocks, and >2.0 for intensely altered rocks. Downhole profiles of alteration intensity generated from systematic pXRF analysis of drill core surfaces can be used to inform drilling and targeting decisions. The application of the Rb/Sr ratio as a proxy for alteration intensity extends beyond this case study and can be applied to other hydrothermal systems that produce phyllosilicate minerals as alteration products of feldspar.

Characterization and Process Optimization in the Extraction of Gold

2015 ◽  
Vol 1087 ◽  
pp. 236-240
Author(s):  
Pek Ling Ong ◽  
Norlia Baharun ◽  
Suhaina Ismail
Keyword(s):  
Response Surface Methodology ◽  
Optimum Condition ◽  
Response Surface ◽  
Room Temperature ◽  
Statistical Approach ◽  
Fluorescence Analysis ◽  
X Ray ◽  
Steepest Ascent ◽  
Refractory Gold ◽  
Central Composite

Refractory gold ore understudied showed traces amount of gold from X-ray fluorescence analysis. Phases identified are quartz, muscovite and calcite. Statistical approach using response surface methodology - central composite design were performed at varying concentration of NaCN, Pb (NO3)2 and H2O2. Cyanidation experiments were conducted at room temperature at pH 11. Using the response surface methodology followed by path of steepest ascent, gold cyanidation was found to be at 467.3 ppm NaCN, 94.96 ppm Pb (NO3)2 and 0.01M H2O2, at the vicinity towards the optimum condition where 88.97% Au extracted from the ore, equivalent to 1.7231 g/t Au.

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