Atmospheric Air Samples Research Articles

Gas Chromatographic Detector for Selective and Sensitive Detection of Atmospheric Organic Nitrates

A highly selective and sensitive detector for measuring organic nitrates in atmospheric air samples has been developed. This detector is based on the luminol chemiluminescence-based detection of NO 2 produced by postcolumn thermal decomposition of organic nitrates. Determination of the relative detector sensitivities to C 3 -C 6 alkyl nitrates, α,β-hydroxy nitrates, α,β-dinitrates, and several mono- and multinitro aromatic compounds as well as N-nitrosodimethylamine has been conducted. The detector is shown to produce one NO 2 per molecule at a pyrolysis temperature of 350 o C, yielding identical sensitivities for alkyl and hydroxy nitrates, consistent with the known thermal decomposition pathway and thermal lifetimes at this temperature

Capillary columns in series for GC analysis of volatile organic pollutants in atmospheric and alveolar air

AbstractAnalysis of volatile organic compounds in air samples requires high resolution capillary gas chromatography. When the sample contains both polar and non‐polar compounds, use of only one type of stationary phase can be unsuitable if it leads to the preferential separation of one kind of component having the same polarity at the expense of the separation of other classes of component.This paper describes the coupling of fused silica capillary columns of different polarity and length in order to achieve the separation of such complex mixtures. The combination is evaluated with a 42 component standard mixture and then applied to various atmospheric air samples and alveolar air of exposed subjects to demonstrate the capabilities of the complete sampling and separation technique.

Application of the CaF 2(Eu) scintillator to 85Kr monitoring in atmospheric air samples

A detection system with a CaF 2(Eu) scintillator has been developed for monitoring β-radiation of 85Kr in atmospheric air samples. The geometry of the detector chamber was optimized to achieve maximum detection efficiency. The design of the detector is described and values of the detection efficiency are presented for various compositions and pressures of the gaseous samples. The conditions for calibration of the detector used for monitoring of 85Kr in enriched air samples have been established.

Measurements of carbonyl sulphide and carbon: Disulphide in the atmosphere

Trace concentrations of atmospheric air samples have been concentrated by the cryogenic trapping technique. Using a flame photometric sulphur detector, the comcentrations of both COS and CS 2 in the atmosphere have been determined. The conributions of these two compounds to the matural annual atmospheric sulphur turnover is shown to be less than 3% of the total.

Gas chromatographic determination of acetic acid in industrial atmosphere and waste water.

A gas chromatographic (GC) method is presented for the specific determination of acetic acid in air and total ionic acetate (as acetic acid) in industrial waste water. Atmospheric air samples are collected in fritted midget bubblers containing aqueous sodium carbonate solution; wastewater samples are treated directly with sodium carbonate. Both air and water samples are concentrated by evaporation of water, and the acetic acid is regenerated by the addition of hydrochloric acid. The amount of acetic acid is determined quantitatively on a porous polymer packed column by internal standardization with propionic acid. GC conditions are described for the suppression of "ghosting" and "tailing" caused by adsorption phenomena associated with the GC behavior of organic acids.

The effect of aniline on photochemical reactions in atmospheric and synthetic air samples

The inhibitory effect of aniline in photochemical smog reactions was studied using actual Toronto air samples. An aniline concentration of 0.81 pphm had negligible effect in a light traffic air sample containing negligible NO, whereas 20 pphm in a heavy traffic sample caused a 70% decrease in the oxidant dosage, a 50% decrease in the NO 2 peak and a four-fold increase in the NO half-life. In experiments with propylene in synthetic mixtures, the half-life of propylene was increased from 144 min. to 192 min. by the present of 20 pphm of aniline. In addition, a thirty-fold increase in condensation nuclei was produced following a one hour induction period. A chemical mechanism is proposed which is consistent with these results. Although the condensation nuclei detected may be too small to produce light scattering, they may be retained in the lung. In addition they may grow in size. These consequences do not favour the use of aniline as an inhibitor in photochemical smog.

Measurement of Growth Rate to Determine Condensation Coefficients for Water Drops Grown on Natural Cloud Nuclei

Abstract Growth rate measurements were made for water drops grown on nuclei in atmospheric air samples taken in Rolla, Missouri. Rolla, having a population of 15,000 and very little industry, is relatively free of urban pollutants. The measurements were made in a vertical flow thermal diffusion chamber at supersaturations of 0.5 and 1%. The time to grow from near dry radius to the final radius (6 to 7.5 µm) was measured. If one assumes the thermal accommodation coefficient is unity, the measurements indicate an average value of 0.026 for the condensation coefficient. The temperature ranged from 22.5 to 25.7°C.

Identification of Carbonic Anhydrase in an Atmospheric Aerosol

BASED on the fact that the measured values of carbon dioxide of atmospheric air samples never could be determined as specific (using Pettenkofer's titration method CO2 values of 0.025–0.037 per cent/vol. were measured) a series of tests have been performed over a period of years to explain these irregularities. While some years ago the influence of light as opposed to darkness and the influence of temperature on the CO2 values could be proved1–3, the existence of a substance which acts as a catalyst and which seems to play an essential part in the deviations of the measured CO2 values was determined by these last tests.

A scintillation counter for the measurement of radon concentration in air

A method is described for measuring the radon content of three litre samples of atmospheric air without pretreatment. The apparatus used consists of a 12 in. photomultiplier with ZnS(Ag) phosphor and counting chamber. A measured efficiency of 38%, when the phosphor is negatively charged, is in good agreement with theory. The ultimate sensitivity is governed by the background which is equivalent to a concentration of 5 × 10-14 cl-1.