One Fe3O4, two birds: Preconcentration and enhanced photochemical vapor generation for the determination of bismuth by atomic fluorescence spectrometry

Fe 3 O 4 was served as an adsorbent and photocatalyst simultaneously in this work, Bi(III) was preconcentrated by Fe 3 O 4 before its photochemical vapor generation-atomic fluorescence spectrometry (PVG-AFS) determination. The experimental conditions including the concentration of formic and acetic acid mixed solution, ultraviolet (UV) irradiation time, the concentration of Fe 3 O 4 and the interferences from the common co-existing ions were explored. The AFS intensity was enhanced slightly by the mixed acid solution (30% (v/v) acetic acid + 5% (v/v) formic acid), while a significant enhancement was observed by using Fe 3 O 4 as photocatalyst with the presence of mixed acid solution, 13-fold enhancement was obtained. The potential enhanced mechanism of Fe 3 O 4 was also discussed here. Fe 3 O 4 was decomposed in the mixed acid solution, Fe 3+ was generated and further served as a sensitizer for improving Bi(III) efficiency. Under the optimized conditions, the limit of detection (LOD) of the proposed PVG-AFS system without or with preconcentration (sample of 5 mL) were 0.44 ng/mL and 0.07 ng/mL, respectively. This PVG-AFS system was successfully applied to the determination of four water samples and their spiked samples, with good recoveries ranging from 94% to 104%, demonstrating a good accuracy and applicability.