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大量锰严重干扰钙,镁络合滴定,必须进行分离。常用的硝酸—氯酸钾法,铜试剂—氯仿萃取法,离子交换法等,手续繁琐。 郑臣林等提出在PH3微醋酸性溶液中,用邻菲罗林-硫氰酸钠沉淀分离锰,其组成为Mn-Phen-CNS。可使高达100毫克的锰完全分离,且钙,镁无损失。当试样中含较高量铁时,须加铜试剂(DDTC)辅助沉淀。但由于少量铁被铜试剂还原后生成[Fe-Phen]_+~2,致使溶液被染成红色,妨碍滴定钙,镁时终点的观察。 本文提出:先在PH6六次甲基四胺介质中沉淀分离铁,铝;然后在同样条件下,用DDTC-Phen-NaCNS沉淀分离锰和其它干扰元素,取滤液进行
A large number of manganese seriously interfere with calcium, magnesium complex titration, must be separated. Commonly used nitric acid - potassium chlorate method, copper reagent - chloroform extraction, ion exchange, etc., procedures cumbersome. Cheng Chenlin proposed PH3 micro-acetic acid solution, with phenanthroline - sodium thiocyanate precipitated manganese separation, the composition of Mn-Phen-CNS. Up to 100 mg of manganese can be completely separated, and calcium and magnesium are not lost. When the sample contains a higher amount of iron, add copper reagent (DDTC) to aid precipitation. However, due to a small amount of iron is reduced by the formation of copper reagent [Fe-Phen] _ + ~ 2, resulting in the solution was dyed red, hinder the titration of calcium and magnesium end of the observation. In this paper, firstly, iron and aluminum were first precipitated and precipitated in the medium of PH6 hexamethyltetramine, and then the manganese and other interfering elements were precipitated by DDTC-Phen-NaCNS precipitation under the same conditions and the filtrate was taken