Which statement about preserved samples is true?

Which statement about preserved samples is true?

• A. Analyzed onsite immediately.
• B. Kept for holding time and often sent to a lab.
• C. Collected over time at constant intervals.
• D. Based on flow.

Answer: (B)

Preserving samples means keeping them in a controlled condition after collection so their quality doesn’t change before analysis. The main purpose is to prevent biological activity, chemical reactions, or volatilization from altering the measured concentrations. Because of this, preserved samples are held for the required holding time and are often sent to a laboratory where the analyses are performed using proper methods and QA/QC. Analyzing onsite immediately wouldn’t involve preserving for holding time. Collecting over time at constant intervals describes how a sample collection is planned (for composites), not how it’s preserved. Sampling based on flow is about when you take samples relative to flow, not how you preserve them. So the statement about preserved samples being kept for holding time and often sent to a lab is the correct description.

Preserving samples means keeping them in a controlled condition after collection so their quality doesn’t change before analysis. The main purpose is to prevent biological activity, chemical reactions, or volatilization from altering the measured concentrations. Because of this, preserved samples are held for the required holding time and are often sent to a laboratory where the analyses are performed using proper methods and QA/QC. Analyzing onsite immediately wouldn’t involve preserving for holding time. Collecting over time at constant intervals describes how a sample collection is planned (for composites), not how it’s preserved. Sampling based on flow is about when you take samples relative to flow, not how you preserve them. So the statement about preserved samples being kept for holding time and often sent to a lab is the correct description.