On-site determination of total dissolved inorganic arsenic in natural waters by a portable atomic fluorescence spectroscopy

The determination of total arsenic across diverse environmental matrices remains a significant challenge. To address the spatial and temporal delays and interference from complex field matrices inherent in traditional laboratory analysis methods, this study developed a continuous, automated, and long-term monitoring system for total dissolved inorganic arsenic (TDIAs). The system enables on-line real-time monitoring of TDIAs in natural waters. Through optimizing the instrumental parameters and chemical vapor generation conditions, the reaction kinetic process of As(Ⅴ) pre-reduction process was thoroughly investigated. In addition, a workflow for the on-site determination of TDIAs in natural waters was designed, including on-line filtration, sample acidification, pre-reduction, analytical detection and single-point calibration. The results demonstrated that the limit of detection (LOD) reached as low as 0.005 μg/L, with a linear range of 0.0–5.0 μg/L under the optimal parameter conditions, and the relative standard deviations (RSDs) were in the range of 0.6 %–7.3 %, which demonstrated a good analytical precision. The method validation showed that the recoveries of different matrix samples, such as tap water, lake water and seawater, were stable in the range of 97.8 %–107.8 %, which proved that the method has excellent ability of resisting matrix interference. Finally, the method has been successfully applied to the on-site determination of TDIAs in the Jinjiang River Estuary, Quanzhou Bay.