Accurate surface tension and charge determinations from polarographic drop-times

1967 ◽  
Vol 45 (2) ◽  
pp. 109-116 ◽  
Author(s):  
R. G. Barradas ◽  
F. M. Kimmerle
Keyword(s):  
Mathematical Method ◽  
Surface Tension ◽  
Hydrochloric Acid ◽  
Potassium Chloride ◽  
Precise Determination ◽  
Surface Tension Data ◽  
Surface Active ◽  
Mercury Electrodes ◽  
Surface Active Compounds

The precise determination of drop-times for micropolarographic mercury electrodes in aqueous inorganic electrolytes with and without the addition of organic surface-active compounds is described. A dependable mathematical method for conversion of drop-times to accurate surface tension data and the use of IBM computer techniques for the calculation of double layer parameters are discussed. Experimental results for hydrochloric acid, potassium chloride, and furfurylamine systems are reported.

scholarly journals Aerosol hygroscopicity at high (99 to 100%) relative humidities

2009 ◽  
Vol 9 (4) ◽  
pp. 15595-15640 ◽  
Author(s):  
C. R. Ruehl ◽  
P. Y. Chuang ◽  
A. Nenes
Keyword(s):  
Surface Tension ◽  
Inorganic Compounds ◽  
Droplet Diameter ◽  
Pure Water ◽  
Sodium Dodecyl ◽  
Bulk Solution ◽  
Active Compounds ◽  
Surface Active ◽  
Surface Active Compounds ◽  
Aerosol Hygroscopicity

Abstract. The hygroscopicity of an aerosol largely determines its influence on climate and, for smaller particles, atmospheric lifetime. While much aerosol hygroscopicity data is available at lower relative humidities (RH) and under cloud formation conditions (RH>100%), relatively little data is available at high RH (99.2 to 99.9%). We measured the size of droplets at high RH that had formed on particles composed of one of seven compounds with dry diameters between 0.1 and 0.5 μm, and calculated the hygroscopicity of these compounds. We use a parameterization of the Kelvin term, in addition to a standard parameterization (κ) of the Raoult term, to express the hygroscopicity of surface-active compounds. For inorganic compounds, hygroscopicity could reliably be predicted using water activity data and assuming a surface tension of pure water. In contrast, most organics exhibited a slight to mild increase in hygroscopicity with droplet diameter. This trend was strongest for sodium dodecyl sulfate (SDS), the most surface-active compound studied. The results suggest that partitioning of surface-active compounds away from the bulk solution, which reduces hygroscopicity, dominates any increases in hygroscopicity due to reduced surface tension. This is opposite to what is typically assumed for soluble surfactants. Furthermore, we saw no evidence that micellization limits SDS activity in micron-sized solution droplets, as observed in macroscopic solutions. These results suggest that while the high-RH hygroscopicity of inorganic compounds can be reliably predicted using readily available data, surface-activity parameters obtained from macroscopic solutions with organic solutes may be inappropriate for calculations of the hygroscopicity of micron-sized droplets.

Polarographic Determination of Niacinamide in Multivitamin Preparations

1974 ◽  
Vol 57 (4) ◽  
pp. 910-913
Author(s):  
Albert Y Taira
Keyword(s):  
Hydrochloric Acid ◽  
Sodium Bicarbonate ◽  
Potassium Chloride ◽  
Chloride Solution ◽  
Mercury Electrode ◽  
Sodium Bicarbonate Solution ◽  
Potassium Chloride Solution ◽  
Microbiological Methods ◽  
Dropping Mercury Electrode

Abstract Niacinamide is extracted from multivitamin preparations with sodium bicarbonate solution. The extract is mixed with Celite and packed into a chromatographic column. The vitamin is eluted with 10% re-propanol in ether and the eluate is evaporated to dryness in the presence of hydrochloric acid. The residue is dissolved in potassium chloride solution and diluted to volume. The polarogram, from –1.40 to –1.90 v, is recorded on a polarograph equipped with a dropping mercury electrode and an H-cell with a saturated calomel reference cell. Additional assays with chemical and microbiological methods showed comparable results. The method is sensitive to 2 mg niacinamide.

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