Matrix-Assisted Photochemical Vapor Generation for the Direct Determination of Mercury in Domestic Wastewater by Atomic Fluorescence Spectrometry

In this article, matrix-assisted photochemical vapor generation is proposed for the direct determination of mercury in domestic wastewater by atomic fluorescence spectrometry. With the ultraviolet light irradiation, the matrix (low-molecular-weight organic compounds) in domestic wastewater samples can produce reducing species. These reducing species could reduce mercury from mercury (II) to elemental mercury, subsequently swept by argon to atomic fluorescence spectrometry for detection. The effects of several factors, such as material of the photoreaction coil, ultraviolet light wavelength, ultraviolet light irradiation time, and flow rate of carrier gas, were investigated. Under the optimized condition, a limit of detection of 0.1 µg L^?1 was obtained. The standard addition method was used for the spiked mercury domestic wastewater sample analysis, with a relative standard deviation (n = 11, at 20 µg L^?1) of 4.8%, and recovery test results ranged from 81% to 110%. The proposed method was applied to analyze two certified reference materials and four domestic wastewater samples, with analytical results in good agreement with certified values or those obtained by ICP-MS. Interferences from common transition metals and alkaline metals as well as alkaline earth metals were also investigated. This is a simple, reagent-free, cost-effective, green method for mercury determination in domestic wastewater.