A gas Chromatographic method is described which permits the direct measurement of the activities of neutral organic compounds in aqueous electrolyte solutions. This method has a relative precision of about 0.5%; it is convenient and fairly rapid, and the apparatus required is relatively inexpensive. The significance of such activity measurements to electrosorption studies of organic compounds on electrodes is discussed. The method is equally applicable to organic compounds which are either liquid or solid in the pure state at the temperature of the electrosorption studies. It may also be used to determine the complete activity‐composition phase diagrams of two component mixtures of the organic compound and water.
A direct reading emission spectrometer system is described which permits dynamic background correction measurements at each analytical wavelength. The system utilizes a refractor plate mounted on a tuning fork as a rapid means for square-wave shifting the spectral band pass from each analytical wavelength to the adjacent background wavelength position. A laboratory computer controls the system, receives the data, and performs the background subtraction. Evaluation of the system has shown that photon counting statistics are applicable and that reliable background corrections are obtained. Comparisons of this correction approach with others that have been used have further demonstrated its advantages for multielement analysis by emission spectrometry.
It has been confirmed that the size distribution of the analyte contained in an aqueous aerosol is affected by the chemical composition of the solution nebulized. The present work has shown that the addition of sodium to copper solutions shifts the aerodynamic and physical size distributions for the copper upward, while the sodium size distributions remain relatively constant. Examination of solid aerosols produced by flash evaporation of aqueous droplets has indicated that the particles tend to be hollow spheres which may encapsulate smaller spheres, as has been observed for particles emitted from combustion sources. The possible significance of droplet evaporation during aerosol transport is examined and judged to be a plausible and at least partial cause of the effects observed.
The effects of nebulization conditions on the size characteristics of the aqueous aerosol produced have been investigated for a cross-flow nebulizer. It is shown that the nebulizer gas flow rate does not affect the upper limit mean sizes of the aqueous droplets transported from the nebulization chamber but that the mean size of the analyte-containing aerosol itself is affected. Model equations are presented descriptive of the effects of gas flow rate and analyte concentrations on analyte aerosol size characteristics.
This paper describes the results of the first stage of an investigation designed to extend present knowledge of the factors affecting aerosol production, transport, vaporization, and atomization in analytical spectroscopy systems. It focuses on factors controlling aspiration of aqueous solutions. The results demonstrate that the effect of gas flow on the pressure drop induced at the tip of the solution draw tube can be described by a simple linear equation; that the relationship between gas flow rate and solution nebulization rate can also be modelled by a simple equation; and that these relationships are not adequately represented by the Hagen-Poiseulle equation, as is often claimed.
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