Hach 1950Plus Instrument Manual page 163

UVTOCGlossary.fm
zero water — water to be used for the preparation of standard solutions.
It should be distilled, deionized, and acidified with phosphoric acid to a
pH of 2 or less, and purged sufficiently with CO
dissolved CO .
2
Appendix C
free gas to drive off any
2
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Glossary