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对食品工业用煤中的有害物质的要求较严,如酿造和食品工业用煤的含砷量不得大于6ppm。煤中微量砷的测定一直沿用煤中测硫的制样方法,即煤样与艾氏剂一起高温灼烧,然后按DDC银(二乙基二硫代氨基甲酸银)光度法测定。由于硫与砷的性质差异较大,采用艾氏剂处理样品,砷的结果明显偏低。我们改用管式电炉加热测定煤中易挥发的砷化物,瓷舟中的灰份用碱熔样,两部分样品合并测砷。测定结果比艾氏剂法高出2.2倍。所用加热玻璃仪器(包括表面皿)均改用瓷蒸发皿,因为玻璃仪器中含有砷,干扰煤中的测定。
Harmful substances in the food industry with more stringent requirements, such as brewing and food industry with arsenic content of coal shall not exceed 6ppm. Determination of trace amounts of arsenic in coal has been used in coal sample preparation method for measuring sulfur, ie, coal samples and Aldrin burning with high temperature, and then by DDC silver (diethyl dithiocarbamate silver) photometric determination. Due to the large differences in the properties of sulfur and arsenic, the use of aldrin treatment samples, arsenic results were significantly lower. We use the tube furnace heating determination of volatile arsenic in coal, porcelain ash in the sample melting with alkali, two parts of the sample combined measurement of arsenic. The result is 2.2 times higher than Aldrin method. All heated glassware (including watchwares) are switched to porcelain evaporating dishes because the glassware contains arsenic that interferes with the determination in the coal.