蔬菜硝酸盐试纸条-反射仪测定法与国标法比较研究

Evaluation of Vegetable Nitrate Analysis Using a Paper Test-strip and Comparison with Standard Analytical Method

选择硝酸盐含量较高和较低的(菠菜和花椰菜)蔬菜为供试材料,对蔬菜硝酸盐标准测定方法(GB/T15401-94)与试纸条-反射仪测定方法的测定结果进行了比较研究,探讨试纸条-反射仪速测方法测定蔬菜硝酸盐含量的准确性以及影响测定的因素。结果表明,蔬菜汁液的颜色对速测有一定的影响,测定过程中需采用活性炭过滤。试纸条-反射仪速测方法与标准方法测定值虽有显著性差异,但二者相关显著,相关系数达到0.84以上。如果采用与国标方法相同的蔬菜打浆液前处理过程,试纸条法速测结果与标准方法测定值相关系数可达0.9以上,并且两种方法的测定值之间没有显著性差异。蔬菜打浆液经过提取、过滤等前处理后,直接用试纸条-反射仪法进行测定,测定结果准确度较高,在科研和食品检测中有一定应用价值。

Quicktest technologies become more and more important in food examination and it is necessary to study the feasibility of quicktest method in monitoring nitrate content of fresh vegetables. A paper test-strip technology, used in conjunction with a modem hand-held reflectometer, was selected in this study, and spinach and cauliflower vegetables were used as test samples. The quicktest technology was evaluated through the comparison of quicktest analysis results with those of the standard laboratory method （GB/T 15401-94）. Before the experiment, optimized detection limits for quicktest method and standard method were tested by nitrate standard solution. The results indicated that the two methods had high accuracy in certain limit of nitrate concentration. The color of the vegetable juice influenced the nitrate determination by a paper test-strip. After removal of the color through filtration of activated carbon, the results obtained with strip test and from standard analysis still showed significant differences, however there was a good correlation between the two methods with correlation coefficients of 0.84. When the vegetable samples were extracted and filtrated as the pretreatment procedures of standard method, there were no significant differences between quicktest analysis and standard method, their correlation coefficients being up to 0.9. The paper test-strip technology is time-effective and has the benefit of not generating toxic waste （such as Cd） in nitrate determination of vegetable, suitable for monitoring research if the squashed juice is appropriately pretreated.