Indirect amplification method for determining mercury by direct-current polarography. Application to organomercury compounds

Abstract

An amplification method for the determination of 0.5–70 ppm (2.5 × 10 −6 to 3.5 × 10 −4 M) of Hg(II) is described. Hg(II) is reacted with a slight excess of KI, and the excess iodide is oxidized by bromine water and measured polarographically as iodate with sixfold amplification. Alternatively, the iodate formed is reacted to liberate iodine which is then reduced to iodide, and again oxidized to yield six iodate ions for every iodide ion originally present; 2 Microdetermination of Mercury in Organomercurial Compounds Compound Sample (mg) Hg (%) SD (%) Calcd Found Error Phenylmercuric Acetate 4.682 59.57 60.04 +0.47 0.68 3.690 59.08 −0.49 Fluorescein-mercuric acetate 3.000 47.22 47.09 −0.13 0.64 3.325 47.21 −0.01 4.173 46.33 −0.89 Mercurochrome 6.884 26.72 25.73 −0.99 0.59 5.427 26.12 −0.60 3.180 26.74 +0.02 4.903 26.50 −0.22 4.542 26.88 +0.16 polarographic reduction requires 36 electrons. Oxidation of the excess iodide with periodate yields four iodate ions for every iodide ion and therefore allows 24-fold amplification. Microdetermination of mercury in organomercurials is achieved using the sixfold method following closed flask combustion: the average percentage error for 10 determinations is ±0.40 and the time required for one sample run is 45 min.