A fast and reliable method for quantitative determination of total mercury in vegetables

A cloud-point extraction (CPE) process using the nonionic surfactant, polyethylene glycol tert octylphenyl ether (Triton X-114) was employed for determination of Hg(II) ions in aqueous solutions. The method is based on the ion-pairing reaction of Hg(II) with Pyronin B (PyrB(+)) in the presence of excess iodide at pH 6.0 and extraction of the complex formed. The chemical variables affecting CPE efficiency were studied, and the analytical characteristics of the method were obtained. The calibration curves were linear in the range of 1-40g L-1 with the detection limits of 0.35 and 0.30g L-1 at 556 and 521nm. Selectivity was also tested. The coefficients of variation of the method are 2.4% and 5.2% for five replicate measurements of mercury at levels of 10 and 25g L-1, respectively. The results obtained for two certified reference samples were in a good agreement with the certified values. The method was applied to the determination of total mercury in vegetable samples.