许洋 王智 孙羽婕 田伟 冯德建 周黎黎

摘要：建立离子色谱法测定绿茶中亚硝酸盐和硝酸盐的含量的方法，茶样前处理方式模拟日常饮茶方式制备茶叶浸提液，依次经过 C18柱、Ag 柱和 Na柱净化，直接进样，采用 KOH 梯度洗脱。亚硝酸盐和硝酸盐工作曲线呈良好的线性相关，相关系数分别为0.9999和0.9992;添加三个浓度水平的加标回收率在96.3%～106.0%之间，精密度测试的相对标准偏差（RSD）值均小于5%。采用该方法对市售46个茶叶进行亚硝酸盐和硝酸盐的检测，结果显示各地所采集的绿茶中亚硝酸盐均存在未检出的情况，检出率和检出含量低。但几乎所有的样品中硝酸盐均检出，且有27.8%茶叶样品硝酸盐含量逼近甚至超过250 mg/kg。

关键词：茶叶;亚硝酸盐;硝酸盐;风险

中图分类号： TS272.7;S571.1文献标志码： A文章编号：1674–5124（2021）12–0058–06

Determination of nitrite and nitrate in green tea and exploration of health risk

XU Yang，WANG Zhi，SUN Yujie，TIAN Wei，FENG Dejian，ZHOU Lili

（Standard and Testing Technology of Tea Key Laboratory of Sichuan Province， National Institute ofMearsurement and Testing Technology， Chengdu 610021， China）

Abstract： An ion chromatography method was established to determine the content of nitrite and nitrate in green tea. In the pretreatment of tea samples， tea extracts were prepared by simulating the way of daily tea drinking. After purification on C18 column， Ag column and Na column， samples were directly injected and then eluted by KOH gradient. There was a good linear correlation between nitrite and nitrate working curves， andthecorrelationcoefficientwas 0.9999 and 0.9992，respectively. Therecoveryratesofthethree concentrations ranged from 96.3% to 106.0%， and the relative standard deviations （RSD） of the precision tests were all lower than 5%. The method was used to detect the nitrite and nitrate in 46 tea leaves sold in the market. The results showed that the nitrite in green tea collected from different places had not been detected， and the detection rate and detection content were low. However， almost all nitrates were detected， and the nitrate content in 27.8% of the samples approached or even exceeded 250 mg/kg.

Keywords： tea; nitrite; nitrate; risk

0引言

全世界有30億人饮茶，茶叶的质量安全问题至关重要。医学研究证明摄入过多的硝酸盐，会对人体健康产生危害[1]，硝酸盐在体内还会转化成亚硝酸盐，会增加患消化系统癌症的几率[2-3]。全球各国采取了一系列相关措施控制食品中亚硝酸盐的含量以及水质中硝酸盐的含量，但却迟迟未给出茶叶和茶饮料相应的限量。有研究表明，茶叶中硝酸盐和亚硝酸盐的含量不足以达到人体的每日允许摄入量（acceptable daily intake，ADI）值[4]。但并不意味着我们可以对此安枕无忧，随着茶叶生产中氮肥施用量越来越大[5]，越来越多的茶叶制品（如抹茶、茶粉等）添加在食品中，势必需要制定更高更严苛的质量安全标准来进一步严格把控茶叶质量安全。……