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The Development Of An Indirect Method For The Determination Of Water In Solid And Liquid Materials Using Head Space Gas Chromatography

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Description: The objective of this research was the development of an analytical method for the quantitative determination of water using Head Space Gas Chromatography (HSGC) and the reaction of calcium carbide (CaC$\sb{2}$) and water to produce acetylene. Samples containing water were transferred to a dry vial containing CaC$\sb{2}$ after which the vial was sealed. The acetylene which formed inside of the vial was then measured by HSGC and related back to the amount of water originally present in the sample. Water in 2-propanol was measured accurately for concentrations ranging from 60-400 ppm, with a relative standard deviation below 5% for 10 individual determinations. The technique was also useful for the determination of water in toluene, methylene chloride, hexane and acetonitrile. Measurements at 60 ppm typically had a relative standard deviation ranging from 5-7%. Determinations below 60 ppm for all of these solvents had poor precision. The technique was also shown to be effective with certain types of solid sample materials. The water content of several hydrated organic acids and the sodium salts of organic acids was determined with both the CaC$\sb{2}$ technique and Karl Fischer titration. The results of the determinations with the CaC$\sb{2}$ technique were within $\pm$5% (a relative value) of the Karl Fischer results. The relative standard deviations, obtained from six individual measurements for each of the compounds, were all less than 5%. Eleven commercially available pharmaceutical products were also analyzed by both the CaC$\sb{2}$ technique and Karl Fischer titration. The accuracy and precision of these determinations were also within the range of 5%. Several compounds were incompatible with the technique. Hydrated transition metal salts and p-toluenesulfonic acid yielded results which were higher than expected. The problem was suspected to be a non-specific reaction of CaC$\sb{2}$ with something other than water in the sample, resulting in the formation of additional acetylene.
Language: English
Format: Degree Work