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Neutralized sulfide solution 3%(w/v)

Internal Solution-ID: S5665

Equipment needed: Autoclave
Compound Amount Unit Conc. [g/L] Conc. [mM]
Distilled water 100 ml - -
Na2S x 9 H2O 3 g 30 124.905
1 The sulfide solution is prepared in a 250 ml screw-capped bottle with a butyl rubber septum and a magnetic stirrer. The solution is bubbled with nitrogen gas, closed and autoclaved for 15 min. at 121°C. After cooling to room temperature the pH is adjusted to about 7.0 by adding of sterile 2 M H2SO4 drop-wise with a syringe without opening the bottle.
2 Appearance of a yellow colour indicates the drop of pH to about 8. The solution should be stirred continuously to avoid precipitation of elemental sulfur. The final solution should be clear and is yellow in colour.