Which analyte’s preservation instruction allows an 8-hour delay after acidification for a Winkler titration?

Which analyte’s preservation instruction allows an 8-hour delay after acidification for a Winkler titration?

• A. pH
• B. Nitrite
• C. Sulfate
• D. Dissolved Oxygen

Answer: (D)

Dissolved oxygen is the analyte that has an 8-hour hold after acidification in Winkler titration. In the Winkler method, dissolved oxygen is fixed chemically by forming compounds that can be titrated later, and the sample is acidified to stop biological consumption and stabilize the reactive species. When the sample is kept refrigerated after acidification, it can be analyzed within about eight hours. The other options aren’t measured by Winkler titration in this context, and their preservation rules don’t hinge on an 8-hour window after acidification.

Dissolved oxygen is the analyte that has an 8-hour hold after acidification in Winkler titration. In the Winkler method, dissolved oxygen is fixed chemically by forming compounds that can be titrated later, and the sample is acidified to stop biological consumption and stabilize the reactive species. When the sample is kept refrigerated after acidification, it can be analyzed within about eight hours. The other options aren’t measured by Winkler titration in this context, and their preservation rules don’t hinge on an 8-hour window after acidification.