Bioaccumulation of mercury in Haemulopsis elongatus and Pomadasys macracanthus from the SE Gulf of California: condition indexes and health risk assessment

Baseline study for the total mercury determination in Yemeni fish

The high levels of mercury toxicity in humans make it necessary to monitor mercury levels in food, pharmaceuticals, and the environment to minimize human exposure. Between June 2020 and October 2021, researchers collected 240 fish samples from different locations along the Yemeni coast to evaluate mercury contamination. The Direct Mercury Analyzer was used to determine the concentration of mercury in each sample. To ensure method accuracy, a series of triplicate mercury concentration analyses were conducted. The samples ranged from 2 to 100 ng to determine linearity and repeatability i.e., within-day variation. The results showed a high level of precision, with a correlation coefficient of 0.9990 and a repeatability of 1.34 %-5.62 % RSD range. The method was also highly accurate, as the mercury recovery results from the contaminated fish samples ranged from 96.77 % to 105.14 %. The limits of detection and quantitation of mercury were 0.0015 ppm and 0.0049 ppm, respectively. This allowed the method to detect trace amounts of mercury in fish meat. Mercury concentration in the 240 fish samples did not exceed the FDA, but below the 0.5 ppm specified limit of YSMO.

Sensitive Mercury Speciation Analysis in Water by High-Performance Liquid Chromatography-Atomic Fluorescence Spectrometry Coupling with Solid-Phase Extraction

An efficient method based on high-performance liquid chromatography coupled with atomic fluorescence spectrometry (HPLC-AFS) was successfully developed for the simultaneous determination of four mercury species including Hg²⁺, methylmercury (MeHg), ethylmercury (EtHg), and phenylmercury (PhHg) in water. Samples were enriched and cleaned up with a solid-phase extraction (SPE) pretreatment using a thiol cartridge. Some key parameters including the selection of a SPE cartridge, eluent type, eluent volume, and interference factors were systematically investigated. Chromatographic separation was achieved on a C₁₈ column using a mobile phase consisting of methanol and 60 mmol L^-1 ammonium acetate with 10 mmol L^-1 L-cysteine by gradient elution. Under the optimized conditions, good linearity (r ≥ 0.9991) was observed between 0.20 to 10.0 μg L^-1. The limits of detection were in the range of 0.001 - 0.002 μg L^-1. High recoveries (87.2 to 111%) and good reproducibility (1.1 - 6.5%) were obtained. Such a method is sensitive, selective and accurate, which can be applied to the quantification of mercury species in water samples.