Particle size and composition effects in x-ray fluorescence analysis of pollution samples

Abstract

Emitted x-ray Intensity Is lower for large, dense particles than for the same mass of small, light ones. This effect often Is negligible for submicrometer particles, but can range up to a factor-of-ten error for 10-µ particles. A simple empirical correction factor Is proposed, namely (1 + ba)a, where a is the particle diameter and b Is a coefficient that depends on particle composition and experimental conditions. A table of values for b Is provided for the determination of 48 different elements in 200 compounds, using either a Cror W-target x-ray tube. Formulas are presented for calculating b In other situations. The accuracy of the correction Is discussed.

Measurement Methods to Determine Compliance with Ambient Air Quality Standards for Suspended Particles

“…Particles larger than ~3 urn absorb some of the emitted x-rays for light elements such as sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, and potassium. Methods 647 ' 652674 - 681 have been developed to compensate for this absorption; these methods involve assumptions about particle size and composition that are accurate for most, but not all, cases of ambient air sampling. Deposits on fiber filters experience x-ray absorption biases for light elements because the particles penetrate deep into the filter, and the intervening filter material attenuates the emitted x-rays.…”

Betterment in EDXRF analytical results for compositional characterization of mixed uranium thorium oxide samples with bead specimens compared with pressed pellet specimens

“…The intensity of the analytes, of the same mass, increases with decrease in its particle size . This effect is negligible for submicron particle size specimens . However, it is difficult to get such particle size by physical grinding of the sample.…”

“…The specimen, in any analytical determination, must be true representative of the sample. In XRF analysis, sample homogeneity, particle size, mineralogical effects and flatness of specimen surface are important parameters that determine the quality of analytical results . The major disadvantage of XRF is that the intensity of the analyte X‐ray line is largely dependent on the matrix composition, i.e.…”

“…[15] This effect is negligible for submicron particle size specimens. [11] However, it is difficult to get such particle size by physical grinding of the sample. Moreover, when the pressure during pelletization of the sample is increased, the powder samples try to get more compact by removing the voids.…”

Methods for analyzing the concentration and speciation of major and trace elements in marine particles

“…An electron from an outer shell fills the hole, leading to 400 the emission of a fluorescent X-ray of well-defined energy (Figure 1) particles must be deposited as a uniform layer or film. Second, the thickness of the film must 421 be thin relative to both the penetration depth of the primary X-ray and the depth from which 422 the fluorescent X-rays emerge (Bertin, 1975;Criss, 1976;Dzubay and Nelson, 1975). ED-…”