Development of a Gaseous Nitrous Acid Generation System for Animal Exposure Experiments

Abstract

Although a flow-type generation system for obtaining gaseous nitrous acid (HONO) at parts-per-billion levels has already been reported, higher gaseous HONO concentrations on the order of parts per million (ppm) are necessary for use in animal exposure experiments, which are conducted to examine certain biological effects. We have developed a flow-type generation system to produce gaseous HONO at ppm levels for animal exposure experiments. This system is based on spraying a mixture of aqueous sodium nitrite with an acid in a porous polytetrafluoroethylene tube. Herein, we report the technical details and cautionary notes of the manufacturing of the system. The most technical cautionary note pertains the flow-control method in the tube for the gas and water solution.