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测定氯化鈉含量的方法,中国药典和美国药典均系加一定量的肖酸銀标准溶液使生成氯比銀沉淀后,再用硫氰酸銨液反滴定剩余的硝酸銀液。此法文献上称为弗尔哈德(Volhard)氏法。苏联药典和英国药典均系采用鉻酸鉀为指示剂,直接用硝酸银标准溶液滴定的方法,此法文献上称为摩尔(Mohr)氏法。近来在实际工作中发現,采用中国药典方法測定含量时,有数批检品其含量恰好在不合格的边缘,用中国药典法测定为99.40%;而用重量法或摩尔氏法测定,一般为99.30%左右,则合于中国药典规定。为此,
To determine the content of sodium chloride, both the Chinese Pharmacopoeia and the United States Pharmacopoeia add a certain amount of silver trifluoate standard solution to precipitate chlorine to silver, and then use an ammonium thiocyanate solution to back titrate the remaining silver nitrate solution. This method is called Volhard’s method in the literature. The Soviet Pharmacopoeia and the British Pharmacopoeia both use potassium chromate as indicator and titrate directly with silver nitrate standard solution. This method is called the Mohr’s method. Recently, in practical work, it has been found that when using the Chinese Pharmacopoeia method to determine the content, there are several batches of test products whose content is exactly on the edge of unqualified products. The use of the Chinese Pharmacopoeia method has determined that the content is 99.40%; and when measured by the gravimetric method or the Moore method, it is generally About 99.30%, it is in accordance with the provisions of the Chinese Pharmacopoeia. to this end,