Signal-to-noise ratios, instrument parameters and repeatability of Itrax XRF core scan measurements of floodplain sediments

Abstract

This study used signal-to-noise ratios to assess the effects of increasing Itrax XRF instrument parameters, namely tube voltage, tube current and exposure time, on XRF spectra and measurement repeatability. Tests were performed on cores from British and Irish floodplains.Seven combinations of tube voltage and current and six exposure times were compared using signal-to-noise ratios for eight target elements. Signal-to-noise ratios may be substantially improved by selecting instrument parameters, particularly tube voltage, for specific target elements. They can also be used to assess element profile suitability for interpretation by comparison with the limit of quantification. Repeatability was assessed using the standard deviation of measurements in nine repeat scans. The variation in element levels in the majority of profiles is considerably greater than the variability in individual measurements.

Phosphorus Quantification in Sugar Cane (Saccharum officinarum) Leaves In Vivo by Portable X-ray Fluorescence Spectroscopy

“…These parameters were used to evaluate the gain obtained with the use of vacuum, which resulted in an improvement of approximately 1.6-fold in the SNR, facilitating the detection of the P concentration in sugar cane leaves. The optimization of voltage and current allows optimal equipment performance for the analytical problem . In the same way, for P, the use of vacuum increased the SNR and enhanced the elemental sensitivity, which is highly recommended and essential for light elements, especially those with atomic numbers of <20. , The limits of detection in XRF depend upon the atomic number, due to not only the air attenuation but also the X-ray fluorescence yield of light elements, which is low due to the Auger decay phenomenon …”

Application of XRF Scanning to Different Geological Archives

“…Thus, the DXRF method (Table 2) produces results with higher quality and better precision, exhibiting relatively lower variation amplitude, average values, SD (except for Ca) and CV, especially for light elements such as Si (4.79), K (5.96) and Ti (9.11). Elements measured at 50 kV by DXRF, which are more stable and less influenced by surface roughness and physical properties of core sediments (Guo et al., 2020; Jones et al., 2019), have slightly smaller variation amplitude, lower average values, higher SD and lower CV, except for Ba (CV = 12.28).…”

X-ray Fluorescence Core Scanning for High-Resolution Geochemical Characterisation of Soils

“…Another challenge in modelling semi-quantitative data that arises from the noisy nature of spectroscopic data and count noise. The signal-tonoise ratio for XRF core scanner counts can be as high as 100 for some elements and as low as 18 for others under the optimum measurement conditions [17]. Efforts have been made to characterise this noise and approximate the noise free data by Bloemsma and Weltje [18], but this method requires replicates that are often not carried out by labs to speed up the throughput of cores.…”