Hach-Lange EVITA OXY User Manual - Manual (Page 57)

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Appendix IIb
Zero point check
1 g of sodium sulphite (Na
2
SO
3
) and
1 mg cobalt (II) salt (Cobalt(II)chloride-hexahydrate;
CoCl
2
, 6H
2
O) is added to 1 litre of water to remove
oxygen from the water. The water is then stirred and
oxygen concentration measured in order to check
the zero point.
Source: DS/EN 25814