硝酸-氢氟酸混合酸液是热挤压不锈钢管有效的酸洗液,其酸液中硝酸的准确测定至关重要。本文对几种常用的测定方法进行探讨。试验提出利用硝酸根的氧化性,使硝酸被过量的硫酸亚铁铵还原,,用重铬酸钾标准溶液返滴定过剩的硫酸亚铁铵进行测定。本文对方法进行了条件试验和重现性试验,并拟定了简便易行的操作方法。结果表明,此法具有反应完全,指示剂变色锐敏,重现性好,准确度高等优点。 Nitric acid - hydrofluoric acid mixed acid hot extrusion stainless steel pipe is an effective pickling solution, the acid in the accurate determination of nitric acid is essential. This article discusses several commonly used determination methods. The test proposed the use of nitrate oxidation, nitric acid is excess ferrous sulfate reduction, with a standard solution of potassium dichromate back titration ammonium ferrous sulfate for determination. In this paper, the method of conditional testing and reproducibility tests, and to develop a simple and easy operation method. The results show that this method has the advantages of complete response, sharp color change indicator, good reproducibility and high accuracy.