Extraction of trace amounts of mercury with sodium dodecyle sulphate-coated magnetite nanoparticles and its determination by flow injection inductively coupled plasma-optical emission spectrometry

A new method for solid-phase extraction and preconcentration of trace amounts Hg(II) from environmental samples was developed by using sodium dodecyle sulphate-coated magnetite nanoparticles (SDS-coated Fe3O4 NPs) as a new extractant. The procedure is based on the adsorption of the analyte, as mercury-Michler's thioketone [Hg2(TMK)4]2+ complex on the negatively charged surface of the SDS-coated Fe3O4 NPs and then elution of the preconcentrated mercury from the surface of the SDS-coated Fe3O4 NPs prior to its determination by flow injection inductively coupled plasma-optical emission spectrometry. The effects of pH, TMK concentration, SDS and Fe3O4 NPs amounts, eluent type, sample volume and interfering ions on the recovery of the analyte were investigated. Under optimized conditions, the calibration curve was linear in the range of 0.2–100 ng mL−1 with r2 = 0.9994 (n = 8). The limit of detection for Hg(II) determination was 0.04 ng mL−1. Also, relative standard deviation (R.S.D.) for the determination of 2 and 50 ng mL−1 of Hg(II) was 5.2 and 4.7% (n = 6), respectively. Due to the quantitative extraction of Hg(II) from 1000 mL of the sample solution an enhancement factor as large as 1230-fold can be obtained. The proposed method has been validated using a certified reference materials, and also the method has been applied successfully for the determination of Hg(II) in aqueous samples.