Fig. 1.

Schematic of breath collection system. A sedated, freely breathing macaque is intubated with cuffed endotracheal (ET) tube (A). A nonrebreathing valve (B) is attached to ET tube, and breath is collected into a 5-liter Tedlar bag (C). After 3–5min of breath collection, 3.5–4 liters of breath is collected. After breath collection is complete, the Tedlar bag is disconnected from the nonrebreathing valve, and the shutoff valve (D) to the bag is closed. Within 30 min of breath collection, the push-pull valve (E) is opened. Breath is filtered via 0.22-μm filter (F) and drawn onto a three-bed sorbent tube (G) containing Carbopack Y, Carbopack X, and Carboxen 1000 via vacuum pump.