Detection of Hidden Mercury in Cosmetic Products by Partially Cross-Linked Poly(4-vinylpyridine)/Screen-Printed Electrode

Due to the severe toxic effects of mercury (Hg) and its derivatives, they are strictly prohibited to be used as cosmetics ingredients. Nevertheless, unknown quantities of Hg are formulated in consumer cosmetic products. We demonstrate a disposable screen-printed electrode modified with 1,5-dibromopentane partially (7%) cross-linked poly(4-vinylpyridine) (SPE/pcPVP) system for the detection of hidden concentrations of mercury, [Hg] within cosmetics goods by anodic stripping analysis in 0.01 M KCl + 0.02 M H2SO4 (1M = 1mol dm?3) solution.

The Hg2+ ion in a chloride medium transforms to [HgCl4]2?, which then selectively preconcentrate and electro-deposite as metallic mercury, Hg0 on the cationic SPE/pcPVP (PVP exist as PVP+ in pH < 5). Under optimal conditions, the calibration graph is linear in the window of 25–150 ppb, with a detection limit (S/N = 3) and regression coefficient of 3.21 ppb and 0.9909 respectively for the SPE/pcPVP. Real sample assay results for the three skin-lightening agents are evidence of the precise existence of prohibited Hg (compared with ICP-MS measurements) in the products. This article further cautions the public of Hg toxicity in cosmetics. Since the approach is low cost and disposable, it is highly suitable for unskilled electrochemists.

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