Ultrasonic-assisted dispersive solid-phase extraction of airborne hexavalent chromium: a novel approach to occupational health risk assessment

This study introduces a novel ultrasonic-assisted dispersive solid-phase extraction method for the preconcentration of chromium ions in airborne samples. The method utilizes an engineered sorbent, silver nanoparticle-modified aminated graphene, which exhibits a synergistic effect that enhances chromium extraction. This effect arises from the combined advantages of the high surface area and functional groups of the aminated graphene scaffold and the improved dispersibility afforded by the silver nanoparticles. The sorbent was comprehensively characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to confirm its morphology and elemental composition. The method's applicability was demonstrated through the analysis of occupational air samples. Under optimized conditions, it demonstrated a linear dynamic range of 3-140 µg L^-1 and achieved a significant preconcentration factor of 14.68. The limits of detection and quantification were 0.9 µg L^-1 and 3.0 µg L^-1, respectively, underscoring the method's high sensitivity for trace analysis. Excellent precision was observed, with relative standard deviations of 3.1% (repeatability, intra-day) and 4.2% (reproducibility, inter-day). Accuracy, validated via a spike-recovery test, yielded recoveries between 95.5% and 105% across three concentration levels, confirming the method's robustness and reliability. Finally, the preconcentration method was used for the trace determination of chromium from three sites of cement industry and a welding workshop site with potential occupational exposure. Based on the measured airborne chromium concentrations, the potential carcinogenic and non-carcinogenic risks to exposed workers were evaluated.