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ANALYSIS OF TOTAL SOLIDS BY THE VACUUM ROTARY EVAPORATION METHOD,
AEROSPACE MEDICAL RESEARCH LABS WRIGHT-PATTERSON AFB OHIO
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Two standard solutions containing constituents of different heat sensitivities and four samples of water taken from different sources were analyzed for total solids in duplicate and simultaneously by the standard or direct-heat evaporation method and by the vacuum rotary evaporation method. There was good agreement between the methods in the analysis of total solids of the heat-stable standard mixture, but not in the case of the heat-labile standard urea solution where the recovery error was 12.3 percent for the standard method vs. 0.5 percent for the new procedure. The four samples tested were tap water, Miami River water, water reclaimed from urine via thermoelectric distillation, charcoal-treated and filtered, and chamber atmospheric condensate collected during a 4-man, 14-day chamber test. Generally, in all four water samples, the amount of total solids analyzed by vacuum rotary evaporation was greater than by the standard procedure, especially where volatile organic material definitely was indicated. The accuracy of the analysis by the vacuum rotary evaporation method is due to the immobilization under reduced pressure and temperature of constituents that normally volatize, decompose, or oxidize with heat. The vacuum rotary evaporation method also has a considerable advantage in speed over conventional procedures. Author
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