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光度法测定钡,一般用变色酸的双偶氮衍生物作显色剂,如偶氮胂Ⅲ,二甲偶氮磺Ⅲ等.这类试剂的灵敏度和选择性均不理想,本文采用新试剂DBS-偶氮胂[3—(2-胂酸苯偶氮)-6-(2,6-二溴-4-磺酸苯偶氮)-4,5-二羟基-2,7-二磺酸萘]作显色剂,此显色剂在偶氮基的邻、对位上,引入了吸电子能力很强的溴原子,使其与钡的显色反应具有更高的灵敏度和更优越的选择性,该试剂能与钡形成紫红色络合物,其最大吸收峰为620nm,表观摩尔吸光系数为3.5×10~4,络合比为:Ba∶DBS-偶氮胂=1∶2,方法操作简便,选择性高,可直接用于硅铝钡铁中钡含量的测定,结果良好。
Photometric method for the determination of barium, usually with chromotropic acid disazo derivatives as a color reagent, such as arsenazo Ⅲ, dimethyl azo sulfur Ⅲ etc. Such reagents sensitivity and selectivity are not ideal, in this paper, a new reagent DBS-arsenazo [3- (2-arsonatphenylazo) -6- (2,6-dibromo-4-sulfophenylazo) -4,5-dihydroxy-2,7-disulfo Acid naphthalene] as a color reagent, the developer in the azo group ortho and para position, the introduction of a strong electron-withdrawing bromine atoms, so that the color reaction with barium with higher sensitivity and superiority The reagent can form a magenta complex with barium, the maximum absorption peak is 620 nm, the apparent molar absorption coefficient is 3.5 × 10 -4, and the complexing ratio is Ba: DBS-arsenazo = 1: 2, the method is simple, high selectivity, can be directly used for the determination of barium content in barium aluminum silicon, the results are good.