A novel sample preparation technique has been developed to preserve solid 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+ from water with dithizone, allows for the determination of Hg2+ in environmental samples. Inclusion of Hg(HDz)2 within the polymer matrix enhances the PCPAS signal amplitude over that from the bare Hg(HDz)2 film by almost sixfold. The standard calibration graph of PCPAS signal amplitude as a function of Hg2+ concentration is linear in the concentration range of 5-100 μg/ml. A lower detection limit can be achieved by using a laser of higher power tuned to a wavelength closer to the maximum absorptivity of the excited Hg(HDz)2 complex. A study, conducted to monitor the change in PCPAS signal amplitude obtained for the same sample 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 area for analysis at a later date.

Department of Chemistry

Lai, E.P.C, Wong, B. (Barbara), & VanderNoot, V.A. (Victoria A.). (1993). 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), 1097–1105. doi:10.1016/0039-9140(93)80172-N