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试样经500℃灼烧1h除去有机碳,滴加5%磷酸除去碳酸盐,在氧气流中经1000℃灼烧,将产生的气体先通入碘化钾—碘酸钾溶液中除去硫,然后再将气体通入异丙醇—乙醇—二乙稀三胺吸收液吸收,以百里香酚酞为指示剂,用乙醇钾标准溶液滴定测得固定碳的量。方法检出限为0.03%,线性范围为0.10%—20%,经国家一级标准物质GBW03118和GBW03119验证,测定的准确度和精密度均满足规范要求,本方法可以准确测得石墨矿石中低含量固定碳的量。
The sample was calcined at 500 ℃ for 1h to remove the organic carbon, 5% phosphoric acid was added dropwise to remove the carbonate, which was then heated at 1000 ° C in an oxygen stream to remove sulfur from the potassium iodide-potassium iodide solution Then the gas is passed through an isopropanol-ethanol-diethylenetriamine absorbing solution to absorb thymolphthalein as an indicator, and the amount of fixed carbon is measured by titration with a standard solution of potassium ethoxide. The detection limit of the method is 0.03%, and the linear range is 0.10% -20%. The method has been verified by national standard GBW03118 and GBW03119. The accuracy and precision of the method meet the requirements of the standard. Amount of fixed carbon.