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.