Sampler: glass tube, 7 cm long, 6-mm OD,
4-mm ID, flame-sealed ends, containing two
sections of activated (600 °C) coconut shell
charcoal (front = 100 mg; back - 50 mg)
separated by a 2-mm urethane foam plug. A
silylated glass wool plug precedes the front
section and a 3-mm urethane foam plug
follows the back section. Pressure drop
across the tube at 1 L/min airflow must be
less than 3.4 kPa. Tubes are commercially
available.