Abstract: Whilst the determination of total selenium in glass is of great relevance to environmental purposes, the measurement of the oxidation states of selenium which may arise under different redox conditions may contribute to clarify the mechanisms of color formation. In the proposed method, the determination of total selenium is carried out by hydride generation atomic absorption spectrometry (HGAAS) on three different glasses covering the range of selenium content between 10 and 130 mg/kg of glass. To prevent losses during the decomposition step, selenium is converted into a nonvolatile form as selenate (Se6+). When the sample is decomposed, the HCl solution (c(HCl) = 10 mol/l) is made and selenium is pre-reduced to Se4+ by heating for 2 h at 80°C. The determination of selenium oxidation states requires a stepwise approach. The measurement of Se-0 is based on its insolubility in HF. After the sample is decomposed. Se-0 is filtered off dissolved from the filter with a HBr-Br-2 mixture and finally measured by HGAAS. Se4+ and Se6+ are recovered in the filtrate of the same sample and determined together after conversion of Se4+ into Se6+. Se4+ is determined in the same filtrate by photometry with o-phenylenediamine (OPDA).

Abstract: Within the frame of the requirements set out by the Packaging Directive 62/94, this paper recommends a method for the determination of mercury by cold vapor atomic absorption spectrometry (CVAAS). The study consisted of two ports: (i) a recovery study.; (ii) a collaborative intercomparison carried out on an experimental glass incorporating Hg in traces. During the recovery study the decomposition solution of a Hg free container glass was spiked with known amounts of Hg which were fully recovered by CVAAS. No significant interferences were found from other hydride forming elements. An intercomparison among ten laboratories carried out on a glass incorporating Hg traces showed an acceptable reproducibility (CV 8.9%) at a mean concentration level of 1.10 mg/kg. The determination limit was estimated as 0.1 mg Hg/kg of glass. Inductively coupled plasma optical emission spectrometry (ICP-OES), used as an alternative to CVAAS, showed a limit of determination of 7.2 mg/kg, which was considered quite inadequate, with respect to the average mean value of Hg possibly present in packaging.