Microliter volume determination of cosmetic mercury with a partially crosslinked poly(4-vinylpyridine) modified screen-printed three-electrode portable assembly

We successfully demonstrated microliter (mu L) volume determination of Mercury (Hg) using an in-built screen-printed three electrodes containing partially crosslinked poly(4-vinlyipyridine) (designated as pcPVP) modified carbon-working, carbon-counter, and Ag+-quasireference electrodes (SPE/pcPVP) in a pH 4 acetate buffer solution with 2 M KCl by using the square wave anodic stripping voltammetric (SWASV) technique. Instrumental and solution phase conditions were systematically optimized. Experiments were carried out by simply placing a 500 mu L-droplet of Hg containing real sample mixed with the base electrolyte on the SPE/pcPVP surface. The SPE/Ag+ quasi-reference system shifted the Hg-SWASV detection potential ca. 250 mV positive, but the quantitative current values were appreciably similar to that of a standard Ag/AgCl reference electrode. Under optimal condition, the calibration graph is linear in the window of 100-1000 ppb of the Hg droplet system with a detection limit of 69.5 ppb (S/N = 3). Finally real sample assays were demonstrated for prohibited cosmetic Hg containing skin-lightening agents in parallel with ICP-OES measurements.