离子电极法快速测定榨菜中硝酸盐含量

Rapid Determination of Nitrate Content in Pickled Mustard Tuber by Ion-Selective Electrode Method

建立一种采用离子电极快速测定榨菜中硝酸盐含量的方法。首先组建由硝酸根离子选择电极、参比电极、离子计和计算机构成的测试仪器,然后分析温度、离子强度调节剂及干扰离子对测试的影响,并建立标准曲线和校准方程,最后采用离子电极法测定榨菜成品液和榨菜脱盐液中的硝酸盐含量,并与紫外分光光度法进行比较。结果表明:温度、离子强度调节剂及干扰离子对榨菜中硝酸盐含量的测试影响较小;离子电极法测定结果与紫外分光光度法测定结果的总体平均相对误差为4.247%,相对标准偏差小于2.0%,且t检验的显著性水平大于0.05,2种方法测试结果无明显差异,并且离子电极法测试时间小于15 s。本方法可代替紫外分光光度法作为榨菜中硝酸盐含量的快速测定方法。

An ion-selective electrode（ISE） method was developed for the rapid determination of nitrate in pickled mustard tuber. Firstly, a test instrument consisting of nitrate ion-selective electrodes, reference electrode, ion meter, and computer was assembled. Then the calibration curve was developed and the influence of temperature, ionic strength and interfering ions on the ISE method was analyzed. Lastly, the nitrate content in pickled mustard tuber was determined by the ISE method, and the data obtained were compared with those from conventional ultraviolet spectrophotometry. The results showed that the temperature change did not affect the calibration curve. Addition of ionic strength regulator and the presence of interfering ions had less influence on the standard curve. The average error between the ion-selective electrode method and ultraviolet spectrophotometry was 4.247%, and their relative standard deviations were less than 2.0%. There were no significant differences between the two methods by t-test. The ion-selective electrode method can be an alternative to ultraviolet spectrophotometry for the rapid determination of nitrate content in pickled mustard tuber within 15 seconds.