A rapid screening of fluorine contents in soil with a consideration of chemical binding by wavelength dispersive X-ray fluorescence spectrometry

Highlights: • WD-XRF is proposed as a powerful screening tool for F-contaminated soil. • Two calibration curves were generated depending on the chemical forms of F in soil. • To verify the developed method, 15 soil samples of an F-accident site were used. • CaF calibration curve would be acceptable to screen the F-contaminated soil. Wavelength dispersive X-ray fluorescence spectrometry (WD-XRF) analysis is proposed as a powerful screening tool of fluorine-contaminated soil. Calibration curves of Na-F and Ca-F were compared, which showed that the sensitivity of Na-F was higher than that of Ca-F, thus the reliable dynamic ranges differed, ranging from 0.02 to 0.5% and 0.05 to 5% for Na-F and Ca-F, respectively. The calculated limit of detection (LOD) and the limit of quantification (LOQ) values were 14.7 mg/kg and 49.1 mg/kg for Na-F, respectively, and 51.6 mg/kg and 172.1 mg/kg. A correction factor (CF) was derived to compensate for the interference from iron and was applied to samples having >10% Fe content. The results indicate that the use of the Ca-F calibration curve does not underestimate F contents in soil samples and is suitable for selection of the samples that require a more accurate analysis in widely contaminated sites. To verify the feasibility of the developed WD-XRF analysis tool, 15 soil samples were used, with all 15 samples acceptably screened. These findings can be helpful for screening over larger F-contaminated sites when accidental spillage is occurring and useful for continuous long-term monitoring.