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Fig. 3. The polarographic sulfide sensor (PSS) signal compared to the standard
chemical analysis of sulfide with 2,2 dipyridyl disulfide (2-PDS). A single
injection of anoxic Na2S stock brought the concentration to 100
µmol l1 in 3 ml air-saturated 20 mmol
l1 Tris at pH 7.0. 50 µl aliquot samples of solution were
removed at timed intervals and immediately added to the 2-PDS reaction
mixture. Both methods reported the same change in sulfide concentration over
time due to spontaneous sulfide oxidation and volatilization. Signals were not
influenced by the presence of a polarographic oxygen sensor (POS) or PSS in
the chamber.