Ultraviolet vapor generation atomic fluorescence spectrometric determination of mercury in natural water with enrichment by on-line solid phase extraction

Abstract

A novel method, which coupled an on-line solid phase extraction (SPE) enrichment with ultraviolet vapor generation (UVG) atomic fluorescence spectrometry (AFS), was developed to improve the sensitivity of mercury determination and to remove the interference of some anion and organics to UVG of mercury. A high mercury retention efficiency and maximum exclusion of inorganic and organic matrix in water samples were achieved by using C18 SPE mini cartridge modified with sodium diethyldithiocarbamate (DDTC). Fast and efficient elution from the cartridge was found by using l-cysteine mixing solution. Furthermore, through the investigation of different UV reactor designs, the most important factor was the structure of the reactor (which corresponded roughly to the photon flux) wherein the tubing was sintered into the UV lamp to give the highest UV generation efficiency. The second factor was the materials of the tubing (which roughly corresponded to the working wavelength). Synthetic quartz, characterized by the highest transparency at 185nm, attained the highest UVG efficiency, suggesting that the most favorable wavelength for UVG was 185nm. Under optimum conditions, the achievable detection limit (3σ) with sample loadings of 10.0mL was 0.03ngL−1 and 0.08ngL−1 with different manifolds, respectively. The method was successfully applied to the determination of Hg in tap water, river water and lake water samples.