Which parameter has a regulatory storage time of 14 days?

Which parameter has a regulatory storage time of 14 days?

• A. Alkalinity
• B. Color
• C. Chloride
• D. Nitrate

Answer: (A)

Regulatory storage time is the maximum period a sample can sit before analysis and still yield an representative result, and this depends on how stable the parameter is. Alkalinity is comparatively stable when preserved properly (acidify to pH below 2 and keep refrigerated), so it can be held about 14 days before testing. Color measurements, on the other hand, are more sensitive to time and matrix changes, so they’re typically analyzed sooner. Chloride and nitrate have their own specific hold times that differ from 14 days—chloride samples are often stored longer under proper refrigeration, while nitrate can require analysis within 48 hours or follow other preservation rules—so they don’t align with the 14-day window.

Regulatory storage time is the maximum period a sample can sit before analysis and still yield an representative result, and this depends on how stable the parameter is. Alkalinity is comparatively stable when preserved properly (acidify to pH below 2 and keep refrigerated), so it can be held about 14 days before testing. Color measurements, on the other hand, are more sensitive to time and matrix changes, so they’re typically analyzed sooner. Chloride and nitrate have their own specific hold times that differ from 14 days—chloride samples are often stored longer under proper refrigeration, while nitrate can require analysis within 48 hours or follow other preservation rules—so they don’t align with the 14-day window.