In passive sampling, under what circumstances is it typically preferred over active sampling?

• A. When you need to measure solvent color changes.
• B. For short-term, high-volume monitoring.
• C. When a simple, low-maintenance, or stationary sampling is sufficient.
• D. When continuous real-time data is needed.

Answer: (C)

Passive sampling excels when you want an easy-to-deploy, low-maintenance approach that can be left in place at a fixed location. Because there’s no pump or power required, samplers can sit stationary and quietly accumulate analyte over the deployment period, providing a time-weighted average exposure without active flow control. This makes it a practical choice for long-term monitoring across multiple sites where frequent visits aren’t feasible. If you need continuous real-time data or you must rapidly capture transient spikes, active sampling or real-time monitoring would be more appropriate. Color changes of a solvent aren’t a standard signal for this method, and short-term, high-volume monitoring benefits from active methods to ensure adequate sample collection.