Determination of mercury in water and fish samples by cold vapor atomic absorption spectrometry after solid phase extraction on agar modified with 2-mercaptobenzimidazole

A novel solid phase extraction method for the determination of mercury has been developed. The Hg(II) ions were retained on a mini-column packed with agar powder modified with 2-mercaptobenzimidazole at a flow rate of 6 mL min−1. The retained Hg(II) ions were eluted with 3 mol L−1 solution of HCl and measured by cold vapor atomic absorption spectrometry (CV-AAS). The effect of different variables such as pH, sample flow rate, amounts of 2-mercaptobenzimidazole loaded on agar and SnCl2 concentration was investigated and optimum conditions were established. The calibration curve was linear in the range of 0.040-2.40 ng mL−1 with r = 0.9994 (n = 8). The limit of detection based on three times the standard deviation (3Sb) (n = 10) obtained under optimum conditions was 0.02 ng mL−1. The relative standard deviation (R.S.D.) for the determination of 0.4 and 2.0 ng mL−1 of Hg(II) was 2.6 and 1.9% (n = 8), respectively. The method was successfully applied to determine Hg(II) in water, wastewater and fish samples.