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目的建立快速蒸馏-自动pH电位滴定法测定挥发性盐基氮的方法。方法采用浸渍和过滤的方法预处理样品,使用半自动蒸馏仪快速蒸馏样品滤液,以不加指示剂的硼酸吸收馏出液,使用滴定仪自动完成样品馏出液的pH电位滴定。结果挥发性盐基氮样品滤液的最佳蒸馏时间为3 min,pH电位滴定的终点pH值为5.2,5种肉类样品测定的相对标准偏差(RSD)为1.4%~4.0%(n=7),不同挥发性盐基氮含量的肉类样品测定的平均回收率为99.5%,对9种肉类样品使用本法及国标法分别测定,结果显示两法差异无统计学意义。结论快速蒸馏-自动pH电位滴定法测定挥发性盐基氮具有简单、快速,准确的特点,该法还无需加入指示剂,和国标法相比较具有明显优势,该法适用于各种肉类及肉制品中挥发性盐基氮含量的测定。
Objective To establish a rapid distillation - automatic pH potentiometric titration method for the determination of volatile basic nitrogen. Methods The sample was pretreated by impregnation and filtration. The sample filtrate was rapidly distilled using a semiautomatic distillation apparatus. The distillate was absorbed with unaffected boric acid and the pH potentiometric titration of the sample distillate was performed automatically using a titrator. Results The optimal distillation time for the volatile basic nitrogen-based filtrate was 3 min, and the final pH value of the pH potentiometric titration was 5.2. The relative standard deviations (RSDs) of the five meat samples were 1.4% -4.0% (n = 7 ). The average recoveries of meat samples with different volatile base salt contents were 99.5%. The results of nine samples of meat samples measured by this method and national standard method showed no significant difference between the two methods. Conclusion Rapid distillation - automatic pH potentiometric titration of volatile basic nitrogen has the characteristics of simple, rapid and accurate. The method also need not add indicator, and has obvious advantages compared with national standard method. This method is suitable for all kinds of meat and meat Determination of volatile basic nitrogen content in products.