Trace analysis for chlorinated hydrocarbons in air by quantitative combustion and coulometric chloride determination: application to standardization of vinyl chloride permeation tubes.
Methods for high-temperature combustion of vinyl chloride in air were studied theoretically and two types of gas mixtures were found to give 100% conversion into HCl. The chloride was determined by coulometric titration with silver, in 70% acetic acid. Good agreement between theoretical and experimental results was obtained. Permeation rates of vinyl chloride from fluorinated ethylene propylene permeation tubes were determined gravimetrically and with the coulometric method developed. The standard deviations of the methods were 0.002 and 0.001 microg min respectively for permeation rates of 0.5 microg min when the temperature was controlled to +/- 0.02 degrees . The coulometric mean value was 99.9% of the gravimetric mean; 1 ppm of vinyl chloride in air could be determined coulometrically with a standard deviation of about 0.002 ppm.
Cedergren
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A
Department of Analytical Chemistry, University of Umeå, S-901 87 Umeå, Sweden.
Fredriksson
S A
SA