According to the rules of uncertainty transfer, the relative and absolute uncertainty were calculated and the relative expanded uncertainty of measurement result of nitrate in vegetable is 2.7 mg/L (k=2).

• 根据不确定度的传播规律；计算出相对和绝对扩展不确定度；得到了蔬菜中硝酸盐的相对扩展不确定度为2.；7mg/L(k=2)。