Determination of mercury in fish by photochemical vapor generation graphite furnace atomic absorption spectrometry

Abstract

In this work the determination of mercury in fish samples by photochemical vapor generation (PVG) was investigated. Fish samples were dissolved in tetramethylammonium hydroxide, followed by the addition of n-propanol and water. Standards and samples were exposed to UV radiation in a photochemical reactor and mercury volatile compounds produced in the reactor were carried to a graphite furnace atomic absorption spectrometer (GF AAS) for measurements. The following parameters of the analysis were carefully investigated: sample preparation, the use of low-molecular weight organic compounds, the sample flow rate, carrier gas flow rate, mass of chemical modifiers, and GF AAS temperature program. The calibration curve showed a correlation coefficient higher than 0.99. A characteristic mass of 0.36 ng and a limit of detection of 0.03 μg g⁻¹ were obtained, considering the amount of sample used in the determination (0.10 g). The sample throughput was 2.7 samples per hour (triplicate analysis). The relative standard deviations of the results obtained for three replicates of each sample ranged from 2 to 16%. The efficiency of PVG of Hg was 85% and it was estimated by comparison with conventional chemical vapor generation. The trueness of the method was confirmed by analyzing three certified reference materials. The proposed method was applied for the analysis of four real samples and the concentrations of mercury in these samples ranged from 0.31 to 3.17 μg g⁻¹. The proposed method was simple and accurate, being an efficient alternative for the determination of mercury in fish.