盐酸标定方法和蒸馏装置对凯氏定氮的影响

Effect of the method of hydrochloric acid calibration and distillation apparatus on Kjeldahl determination

文章研究了盐酸浓度标定方法和蒸馏装置对凯氏定氮测定的影响。试验一,采用300℃干燥至恒重的无水碳酸钠作对照,以不同温度和时间处理的硼砂及无水碳酸钠对盐酸浓度标定进行了研究;试验二,比较了全自动凯氏定氮仪和半微量蒸馏装置在测定中的差异性。结果表明:用凯氏定氮法测定饲料中粗蛋白质含量时,盐酸溶液浓度标定方法和蒸馏装置的选择对结果有很大影响,室温存放的硼砂和380℃干燥至恒重的硼砂对盐酸溶液浓度的标定结果与对照组差异不显著(P>0.05),用室温存放的硼砂进行盐酸标定更省时、省事和节能;而全自动凯氏定氮仪对硫酸铵回收率较高更适于科研分析使用。

The experiment researched the effect of the method of hydrochloric acid calibration and distillation apparatus on Kjeldahl determination. Experiment 1： Hydrochloric acid solution concentration calibration were studied through the neutralization with horax and anhydrous sodium carbonate treated with different methods, compared with anhydrous sodium carbonate baked at 300 ℃ to constant weight. Experiment 2： Comparing the accuracy of determination of auto-kjeldahl apparatus with that of semi micro-distillation apparatus. The results showed that when the crude protein in feed was determined through Kjeldahl method, the accuracy of standardization of hydrochloric ac.id solution concentration and the choice of distillation apparatus greatly affected the results. The borax stored at room temperature and 380 ℃ drying to constant weight of borax had no significant effect on the results of calibration of hydrochloric acid solution concentration compared with the control （P〉0.05）. Therefore, this method can be used to determine hydrochloric acid solution concentration, easily operated, saving trouble and saving energy; Auto-kjeldahl apparatus which had a higher recovery rate was relatively suitable for scientific research.