What is the minimum sample volume required for this sampling method?

• A. 1250 Liters
• B. 500 Liters
• C. 1000 Liters
• D. 2000 Liters

Answer: (A)

The main idea here is that you must sample enough air to collect a detectable amount of the target contaminant for the lab method to quantify it reliably. The amount of contaminant collected is the product of the environmental concentration and the volume of air you sample. To ensure the lab can detect and quantify at the lowest concentration of interest, you pick a minimum volume so that the mass collected meets or exceeds the method’s detection limit (MDL). If you sample less air, you may not reach the MDL and results could be nondetect or imprecise. For this method, the calculation based on the MDL and the lowest concentration of interest leads to about 1250 liters as the minimum. Sampling more air can improve precision but takes more time, so 1250 liters is chosen as a practical minimum to achieve reliable detection without unnecessary effort.