A new type of personal sampler for gases in air, originally reported from this laboratory, has been adapted to measurement of NO2. The sampler depends on the transfer of NO2 by diffusion to a triethanolamine coated collector at the sealed end of a tube; the open end of the tube is exposed to the test environment. The devices are accurate, light, simple to use and have very good shelf life before and after sampling.
A personal sampler system for NOx (NO + NO2) and NO2 has been developed for monitoring workplace air. The NO2 sampler previously reported from this laboratory uses triethanolamine to trap NO2 which diffuses through a tube of appropriate dimensions. The NOx sampler contains the same elements as the NO2 device, but it is also fitted with a chromic acid impregnated disc; this disc converts NO to NO2 which is then trapped by the triethanolamine along with preformed NO2. The trapped NO2 in all cases is determined as nitrite colorimetrically and NO is measured by difference between the NOx and NO2 values. The NOx sampler gives accurate and reproducible results if the chromic acid disc is in place for 24 hours or less; it is necessary, therefore, to insert and remove the disc within reasonably short times before and after sampling. We believe, however, that this operation will not be a serious problem for the user.
Mechanical mixture due to pulmonary flow, in contrast to mixing by molecular diffusion within the respiratory spaces, has been studied directly using aerosol inhalation. The technique uses particles, about ½ μ in diameter, which are fairly stable in the respiratory tract, and measures the concentration of aerosol during expiration with a continuous and rapid detector of scattered light and, simultaneously, the expiratory volume flow. The flow component of pulmonary ventilation is described in terms of the fractions of tidal air (Vx) and functional residual air (Vr) which participate in the ventilatory exchange of aerosol. Aerosol clearance experiments on three apparently healthy subjects show these two newly defined mixing volumes (Vx and Vr) to be much smaller than their analogous volumes measured by gas clearance: less than one-third for the fraction of tidal air and less than one-tenth for the fraction of functional residual air. These results demonstrate quantitatively the major role of molecular diffusion in ventilation. This approach provides a new method for the measurement of the mechanical component of intrapulmonary mixing. Submitted on November 3, 1958
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.