novel vapor-generation technique is described for
mercury determination in aqueous solutions. Without
need for a chemical reducing agent, dissolved mercury
species are converted to volatile Hg vapor in a solution
cathode glow discharge. The generated Hg vapor is then
transported to an inductively coupled plasma for determination
by atomic emission spectrometry. Mercury vapor
is readily generated from a background electrolyte containing
0.1 M HNO3. Vapor generation efficiency was
found to be higher by a factor of 2-3 in the presence of
low molecular weight organic acids (formic or acetic acids)
or alcohols (ethanol). Optimal conditions for dischargeinduced
vapor generation and reduced interference from
concomitant inorganic ions were also identified. However,
the presence of chloride ion reduces the efficiency of Hgvapor
generation. In the continuous sample introduction
mode, the detection limit was found to be 0.7 μg L-1, and
repeatability was 1.2% RSD (n ) 11) for a 20 μg L-1
standard. In comparison with other vapor generation
methods, it offers several advantages: First, it is applicable
to both inorganic and organic Hg determination; organic
mercury (thiomersal) can be directly transformed into
volatile Hg species without the need for prior oxidation.
Second, the vapor-generation efficiency is high; the efficiency
(with formic acid as a promoter) is superior to
that of conventional SnCl2-HCl reduction. Third, the
vapor generation is extremely rapid and therefore is easy
to couple with flow injection. The method is sensitive and
simple in operation, requires no auxiliary reagents, and
serves as a useful alternative to conventional vapor
generation for ultratrace Hg determination.