Oltner R, Bengtsson S, Larsson K
Acta Vet Scand. 1985;26(3):396-404. doi: 10.1186/BF03546539.
An inexpensive and easily automated flow injection method for determination of urea in cow’s milk was evaluated. Urea is hydrolysed by urease and in a gas diffusion cell the ammonia formed passes a membrane into an indicator solution. The resulting colour change of the indicator is measured at 590 nm. The repeatability of the analysis, expressed as the coefficient of variation (C.V.), was between 0.5 and 1.2%. Measured (y) and expected (x) milk urea concentrations after addition of known amounts of urea were related according to the equation y = 1.00× – 0.12 with a C.V. for the regression of 1.8%. Recommended amounts (0.02 %) of the preservative bronopol (2-bromo-2-nitropropane-1,3-diol) added to the milk did not affect the results (P > 0.05).
评估了一种用于测定牛奶中尿素的廉价且易于自动化的流动注射法。尿素被脲酶水解，在气体扩散池中形成的氨通过膜进入指示剂溶液。在590nm处测量指示剂产生的颜色变化。分析的重复性以变异系数（C.V.）表示，在0.5%至1.2%之间。添加已知量尿素后测得的（y）和预期的（x）牛奶尿素浓度根据方程y = 1.00× – 0.12相关，回归的C.V.为1.8%。添加到牛奶中的推荐量（0.02%）防腐剂溴硝醇（2-溴-2-硝基丙烷-1,3-二醇）不影响结果（P > 0.05）。
