Rapid Detection of Available Cr(VI) in Soil Based on pXRF Combined with Ion-Exchange Resin

The detection of available Cr(VI) in soil is critical due to its high uptake by plants, which enables it to enter the food chain and pose significant health risks to humans. Traditional detection methods are often time-consuming and labor-intensive, limiting their suitability for rapid, on-site measurements. This study introduces a novel approach for the rapid detection of available Cr(VI) in soil, utilizing portable X-ray fluorescence spectrometry (pXRF) in combination with ion-exchange resin. The method was validated using soil samples from three distinct regions, representing three different soil types. Compared to conventional laboratory methods, the detection rates for Cr(VI) ranged from 80.73% to 124.14%, with relative standard deviations for repeated analyses ranging from 3.05% to 5.73%, both of which comply with national standards. Regression analysis confirms a strong linear relationship between spectral values and Cr(VI) concentration in standard solutions (R 2 = 0.9986). Through resin enrichment, the detection limit (LoD) for Cr(VI) in soil solution reaches 0.070 mg/kg, facilitating trace-level detection of available Cr(VI) in soil. In contrast to traditional methods, the pXRF-ion-exchange resin approach minimizes secondary environmental contamination, is cost-effective and time-efficient, and does not require complex soil pretreatment. Consequently, it is highly suitable for rapid, on-site soil analysis. This study presents an innovative method for the detection of available Cr(VI) in soils. This approach effectively reduced analysis time and simplified sample pretreatment, and thus holds substantial potential for practical application.