靛酚蓝反应测定发酵液中的氨态氮

针对发酵工业中氮源消耗的检测问题,提出了基于靛酚蓝反应的氨态氮定量测定方法.通过优化显色反应时间、颜色稳定性和试剂添加顺序等条件,考察了氨态氮质量浓度与吸光度值之间的关系.采用日内、日间重复实验和回收率实验进行方法学验证.将该法应用于氨基霉素和S-腺苷蛋氨酸发酵生产过程氨态氮的定量测定.结果表明,当氨态氮在0～7mg/L时,质量浓度与显色反应溶液在625nm处的吸光度值具有显著的相关性,相关系数为0.9986,该测定方法具有较高的精确度、精密度和灵敏度,可检测出发酵后期氮源的微量变化,有利于发酵控制策略的调整,提高了产品的产率.

Determination of ammonium nitrogen in fermentation broth through indophenol blue reaction

A novel method for quantitative determinating of ammonium nitrogen was proposed to assay the nitrogen source in the fermentation industry by using the indophenol blue reaction. Optimizing the color reaction time, color stability conditions and the adding order of reactants, the correlation between the ammonium nitrogen concentration and the optical density was investigated. The method was validated through the intra-, inter-day repeatability tests and the recovery test, and determined the ammonium nitrogen concentration during the fermentation process of mildiomycin and S-adenosylmethionine. Results show that in the range of 0~7()mg/L, ammonium nitrogen concentration is significantly linear with the optical density of the reaction solution at 625()nm, and correlation coefficient is 0.998()6. The method has highly precise, accurate and is sensitive to detect subtle change of nitrogen source during the late phase of fermentation. The proposed method facilitate the adjustment of fermentation control strategy and the improvement of productivity.