A Nonrebreathing breath collection system for the study of exogenous and endogenous compounds in the Fisher-344 Rat

Abstract

A nose-only, nonrebreathing breath collection system for use with Fisher-344 rats was developed and characterized. The system is open in design and relies on mass flow controllers to regulate both the introduction of clean, humidified air and the withdrawal of exhaled breath in a balanced fashion. The system accommodates simultaneous collection from three rats held in Battelle-type restrainers modified to include an auxiliary nitrogen purge to minimize the infiltration of volatile organic compounds (VOCs) from the room and excreta into the collected breath. The VOCs in breath were collected onto Tenax or multisorbent cartridges and analyzed by thermal desorption/gas chromatography with flame ionization or mass spectrometric detection. Recoveries through the collection and analysis system for a mixture of chemically diverse standard compounds at 4-10 ng/L each averaged 98%. The administration of carbon tetrachloride dramatically increased the number and amount of VOCs in breath. Increases were measured for hydrocarbons, aldehydes, ketones, and chlorinated species. The composition of these VOCs in breath was observed to be time dependent.