X-ray Fluorescence Results Research Articles

A Portable X-Ray Fluorescence Instrument for Analyzing Dust Wipe Samples for Lead: Evaluation with Field Samples

Dust wipe samples collected in the field were tested by nondestructive X-ray fluorescence (XRF) followed by laboratory analysis with flame atomic absorption spectrophotometry (FAAS). Data were analyzed for precision and accuracy of measurement. Replicate samples with the XRF show high precision with an intraclass correlation coefficient (ICC) of 0.97 (P<0.0001) and an overall coefficient of variation of 11.6%. Paired comparison indicates no statistical difference (P=0.272) between XRF and FAAS analysis. Paired samples are highly correlated with an R2 ranging between 0.89 for samples that contain paint chips and 0.93 for samples that do not contain paint chips. The ICC for absolute agreement between XRF and laboratory results was 0.95 (P<0.0001). The relative error over the concentration range of 25 to 14,200 μg Pb is −12% (95% CI, −18 to −5). The XRF appears to be an excellent method for rapid on-site evaluation of dust wipes for clearance and risk assessment purposes, although there are indications of some confounding when paint chips are present.

Non‐destructive x‐ray fluorescence analysis of soils and friable and marine sediments

AbstractA procedure for the non‐destructive x‐ray fluorescence (XRF) spectrometric determination of major and some minor elements in soils, marine sediments and friable deposits is proposed. It does not require any preliminary treatment of the sample except for its drying at 105°C. The matrix correction procedure used is based on α‐ coefficients which are simulated for maximum possible variations of interfering element concentrations in the matrix and are calculated on the assumption that the sample is homogeneous. The achieved agreement between the XRF results and the certified values is satisfactory. The paper discusses why the above material cannot be homogenized by fusion and the effect of this on the XRF results.

Identification of scale deposits through membrane autopsy

A polyacrylate and hydroxyethylidene diphosphonate (HEDP) based advanced anti-scalant was tested against the conventional H 2SO 4 and sodium hexa-meta-phosphate (SHMP) inhibitors in a pilot plant which had parallel RO units, each fitted with identical hollow fine fiber (HFF) permeators which received same brackish feed water. At the end of the 3000 h trial, product TDS of unit #2 operating on the conventional treatment was only 180 ppm vs 620 ppm for unit #1 operating on the advanced anti-scalant, and it produced an average of 20% more product water. To identify the scale deposits, autopsy of the first and second stage permeators was carried out using visual observation, scanning electron microscopy (SEM), x-ray diffractometry (XRD), x-ray fluorescence (XRF), inductively coupled plasma (ICP) spectroscopy, ion chromatography (IC), and coulometry techniques. Whereas thick deposits of soft and non-adherent types of scales were found on the permeator fibers of unit #1, no scale was evident on unit #2 permeator fibers and no samples could be collected from them. Analyses of the solids removed from the unit #1 fibers revealed that bulk of the deposited scale was amorphous in nature which the SEM and XRD techniques were unable to charaterize. The XRF, ICP, and IC results suggested that the amorphous sludge was predominantly alumino-silicate type. In addition, membrane fibers of stage 1 had calcium/magnesium phosphonate, formed by the advanced anti-scalant itself by reacting with Ca 2+ and Mg 2+ of the brine. No CaCO 3, SrCO 3, CaSO 4, SrSO 4, or iron-based scales were detected, indicating that the advanced anti-scalant was effective against these scales.

Sources and composition of aerosol from Khartoum, Sudan

Aerosol sampling was carried out during December 1989 in Khartoum, Sudan, using Nuclepore membrane filters. Twenty-four aerosol samples were collected and analysed by X-ray fluorescence (XRF) spectrometry and particle-induced X-ray emission (PIXE). In addition, individual particle analysis was also performed on 19 samples using electron probe X-ray microanalysis (EPXMA). Good agreement between XRF and PIXE results was obtained for most of the elements. Enrichment factor calculations indicated that soil dispersion is the dominant source for most elements in the aerosol. However, certain elements showed high enrichment factors indicating the presence of anthropogenic sources. From a comparison with available literature data it appeared that the enrichment factors for the enriched elements in the Khartoum aerosol are among the lowest recorded values for urban aerosol. Absolute principal components analysis (APCA) was performed on the data and confirmed the findings from the enrichment factor calculations, i.e. a dominant soil dispersion source and an anthropogenic source for some of the elements. Because of the very limited number of impotant aerosol sources, the data set was reporduced by the APCA model with a reasonable degree of success. Single particle analysis also showed that most of the particles were soil dust. These particles could further be differentiated into alumino-silicates, quartz and CaCO 3 particles. Some of the particles were found to originate from combustion sources. EPXMA gave clues to the process of formation for some of the particles from combustion sources.

Dependence of the accuracy of the results of steel x-ray fluorescence analysis on the method of considering the variation of α coefficients with sample chemical composition

The accuracy of the results of steel x-ray fluorescence (XRF) analysis using certain computation algorithms, differing in the way in which they consider the dependence of α coefficients on sample composition, was compared by means of the determination of chromium in steel standard samples, the chemical compositions of which represent possible compositional variations of 456 different types of high-speed, high-, medium- and low-alloy steels. It is shown that in the XRF analysis of steels, the best accuracy is provided by algorithms in which this dependence is based on real variations in the concentration of interfering elements. Algorithms using constant influence coefficients may also give acceptable accuracy of XRF results provided that more exact calculation of equation parameters, by which the values of reduced element concentrations are obtained, are found. Recommendations for increasing the accuracy of these parameter calculations are given.

NON-DESTRUCTIVE ANALYSIS OF ANCIENT BRONZES

In this paper are described the measurements, carried out on a considerable number of ancient bronzes, using a portable radioisotope X-ray fluorescence (XRF) unit. This unit allows, in a non-destructive way, the quantitative determination of copper, zinc, tin and lead in bronzes and brasses, in a measuring time of about 100 seconds. The XRF results are in good agreement with those obtained by traditional methods.