微波消解凯氏定氮法快速测定酱油中全氮

研究了凯氏定氮法测定酱油中全氮时样品的微波消解方法，进行了微波消解条件的选择及消解结果精密度试验，并与国家标准方法对比，验证了方法的准确度。试验结果表明，消解完全仪需20min，相对标准偏差均小于2%（n=7），回收率范围为96%～103%，经t检验，微波溶样法与国家标准凯氏定氮法的测定结果无显著性差异。

RAPID DETERMINATION OF TOTAL NITROGEN IN SOY SAUCE BY KJELDAHL METHOD WITH MICRO-WAVE HEATED SAMPLE DIGESTION

Digestion of soy sauce sample by heating with microwave was studied and used in combination with the Kjeldahl method for determination of total nitrogen. It was found that the sample was digested completely in 20 min by micro-wave heating. Precision test was made on 3 samples of different brands, values of RSD's calculated from the results of 7 determinations for each sample were found less than 2%. To 100 mL of different soy sauce samples, portions of 0. 50 g of nitrogen [added as (NH4)2SO4] were added for test of recovery, results obtained were in the range of 96% -103%. In the analysis of 7 samples of soy sauce of different brands for their total nitrogen contents by both the method presented in this paper and the method given in GB/T 18186 - 2000, the results obtained were in consistency with each other, and no significant difference was found by the result of t-test.