天青石中钡和锶的容量法测定,通常是采用将二、三氧化物和钙、镁分离后用EDTA络合法测定钡和锶的总量,另分取溶液沉淀铬酸钡,酸溶解后用碘量法或络合法测定钡,差减求出锶的含量。此法手续冗长,不适于钙含量较高的样品分析。根据铬酸钡和铬酸锶的溶度积相差较大,我们提出从均匀溶液中分别置换沉淀铬酸钡和硫酸锶并连续间接滴定钡、锶的容量法。即pH10时,在Zn-EDTA存在下以EDTA滴定钡、锶和其它碱土元素,然后分别以已知(过量)体积的氯化镁-重铬酸钾溶液和硫酸锌从均匀溶液中用置换反应产生铬酸钡租铬酸锶沉淀,反应式如下: Celestite and barium strontium volumetric method for the determination of usually two, three oxide and calcium, magnesium after the determination of the total amount of barium and strontium with EDTA complexation method, and the other solution was precipitated barium chromate, acid dissolved After the iodometric method or complex method for the determination of barium, the difference was calculated strontium content. This method is lengthy, not suitable for high calcium content of the sample analysis. According to the large difference between the solubility products of barium chromate and strontium chromate, we propose that the volumetric method of continuous and indirect titration of barium and strontium should be separately replaced from the homogeneous solution by barium and strontium sulfate. Ie at pH 10, barium, strontium and other alkaline earth elements are titrated with EDTA in the presence of Zn-EDTA and then replaced by a displacement reaction with a known (excess) volume of magnesium chloride-potassium dichromate solution and zinc sulfate, respectively, to produce chromium Barium lean strontium precipitation, the reaction is as follows: