氨气敏电极法测定土壤全氮

用氨气敏电极测定土壤全氮,方法简单、快速、准确,操作安全,无需蒸馏和滴定。按照本文拟定的方法:首先在消解的溶液中加入10M 的 NaOH,使溶液近中性,以免测定时因待测液中加大量浓 NaOH 而引起液温剧烈变化。我们所制备的电极内充液可以减小电极薄膜内外两边溶液的渗透压差别。因此,所述方法测定土壤全氮要比一般氨气敏电极法更为准确。用所述氨气敏电极法和常用的开氏蒸馏法对17个含氮范围很广的土样测定所得的结果完全一致。因而所述方法适宜于批量土样全氮的测定。

TOTAL NITROGEN IN SOILS DETERMINED BY MEANS OF THE AMMONIA-SENSING ELECTRODE

The ammonia-sensing electrode used in determining total nitrogen in soils is simple,fast,accurate and safe to handle without distillation and titration. According to the method suggested in this paper,10 M NaOH should be, first of all,added to the digested soil solution so as to make it roughly become neutral lest a drastic rise in temperature should occur when a large amount of concentrated NaOH is added to soil solution in determination. Electrodes prepared by us are filled with ions which can minimize the def- erences of osmatic pressure on both the inside and outside solutions of thin membrance of the electrodes.Thus,the method described here is more accur- ate in determining total nitrogen in soils than the usually ammonia-sensing electrode method.17 soil samples with a wide range of N contents were determined by the above-described ammonia-sensing electrode method and Kjeldahl distination method,and their results are entirely agreeable with each other.Thus far,the method described is suitable to the determination of total N of a mass of soil samples.