ABSTRACT
Air is pumped at a sampling rate of approximately 100–200 mL/min through a trap containing 200 g of desiccant that collects moisture from the air. This method describes the use of silica gel as the desiccant. However, other common desiccants such as molecular sieves (alumino-silicates), anhydrous calcium sulfate, and activated alumina can be used. The stated flow rate is sufficient to allow continuous air sampling for 1–2 wk at 50% relative humidity. Other methods of moisture collection such as cold traps, bubblers and dehumidifiers may also be used for short-term sampling with various effects on measurement accuracy, depending on completeness of collection (6).
