碱性次氯酸钠-苯酚分光光度法测定甲醇处理的瘤胃液中氨态氮浓度

[目的]建立一种适于测定用甲醇处理的瘤胃液中氨态氮浓度的碱性次氯酸钠-苯酚分光光度法方法.[方法]比较加或不加甲醇对标准氨态氮线性回归方程的影响,对比色波长、显色稳定性进行测定,进行回收率、精密度试验,并用建立的方法实际测定甲醇处理的绵羊癌胃液中氨态氮浓度.[结果]反应物在37℃水浴10 min、室温下放置10 min后显色更加稳定,最大吸收波长为650nm;氨态氮浓度在1～32 mg/100 mL时与650nm处吸光度值的相关系数为0.9999,回收率97.2;～103.7;(平均为99.9;);标准溶液和样品溶液的吸光度值日间变异系数、日内变异系数均小于5;.[结论]在样品液中含有50;体积比例的甲醇对碱性次氯酸钠-苯酚分光光度法测定氨态氮浓度没有影响,可用于经甲醇处理的瘤胃液中氨态氮浓度的测定.

Determination of Ammonia-nitrogen in Ruminal Fluid Treated with Methanol by Alkaline Hypochlorite-Phenol Spectrophotometry

【Objective】This experiment was conducted to establish an assay suitable for determination of ammonia-nitrogen in ruminal fluid treated with methanol by alkaline hypochlorite-phenol spectrophotometry.【Method】The effects of adding or not adding methanol to the ammonia-nitrogen standard solution were conducted on equation of linear regression.The absorption spectrum and stability of chromophore were determined.The recovery rate and precision of this method were also determined and it was used to determine ammonia-nitrogen concentration in ruminal fluid treated with methanol.【Result】The maximum absorption wavelength is 650 nm.The chromophore was stable at least for 1 h after the mixtures reacted for 10 min at 37℃ and stood for 10min at room temperature.The correlation coefficient was 0.999 9 between absorption at 650 nm and ammonia-nitrogen concentration in the range from 1 mg/100 mL to 32 mg/100 mL.The recovery rate was 97.2%-103.7%(with an average of 99.9%).The coefficient of absorbance variation inter-day and within-day were less than 5% for standard solution and sample.【Conclusion】There was no significant influence on determination of ammonia-nitrogen when methanol in ammonia-nitrogen standard solution was 50%(volume/volume),therefore,the alkaline hypochlorite-phenol spectrophotometry could be used to determine ammonia-nitrogen concentration in ruminal fluid treated with methanol.