钝化液中硝酸含量的测定是某厂化验室长期存在的生产关键问题。钝化液中含有硝酸、硫酸及三氧化铬,其中硝酸含量的测定因三氧化铬含量较高(200克/升),致使长期没有可靠的分析方法而影响生产。虽然有一个方法,但因 CrO_3含量较高,他们用 BaCrO_4分离法,因 BaCrO_4溶度积较大(SpBaCrO_4= Determination of nitric acid in passivation solution is a long-standing production of a laboratory laboratory key issues. Passivation solution contains nitric acid, sulfuric acid and chromium trioxide, of which the determination of nitric acid content due to the high content of chromium trioxide (200 g / l), resulting in long-term no reliable analytical methods and affect the production. Although there is a method, but because of high CrO_3 content, they use BaCrO_4 separation method, due to BaCrO_4 solubility product larger (SpBaCrO_4 =