PRESERVATION OF SOLID MERCURIC DITHIZONATE SAMPLES WITH POLYVINYL-CHLORIDE FOR DETERMINATION OF MERCURY(II) IN ENVIRONMENTAL WATERS BY PHOTOCHROMISM-INDUCED PHOTOACOUSTIC SPECTROMETRY
Epc. Lal et al., PRESERVATION OF SOLID MERCURIC DITHIZONATE SAMPLES WITH POLYVINYL-CHLORIDE FOR DETERMINATION OF MERCURY(II) IN ENVIRONMENTAL WATERS BY PHOTOCHROMISM-INDUCED PHOTOACOUSTIC SPECTROMETRY, Talanta, 40(7), 1993, pp. 1097-1105
A novel sample preparation technique has been developed to preserve so
lid mercuric dithizonate [Hg(HDz)2] in a matrix of polyvinyl chloride
(PVC) for analysis by photochromism-induced photoacoustic spectrometry
(PCPAS). This technique, which begins with the extraction of Hg2+ fro
m water with dithizone, allows for the determination of Hg2+ in enviro
nmental samples. Inclusion of Hg(HDz)2 within the polymer matrix enhan
ces the PCPAS signal amplitude over that from the bare Hg(HDz)2 film b
y almost sixfold. The standard calibration graph of PCPAS signal ampli
tude as a function of Hg2+ concentration is linear in the concentratio
n range of 5-100 mug/ml. A lower detection limit can be achieved by us
ing a laser of higher power tuned to a wavelength closer to the maximu
m absorptivity of the excited Hg(HDz)2 complex. A study, conducted to
monitor the change in PCPAS signal amplitude obtained for the same sam
ple over an extended storage period of 19 days, demonstrates that the
PVC protects the integrity of the solid Hg(HDz)2 sample. Hence, it is
potentially feasible to collect environmental samples from a remote ar
ea for analysis at a later date.