Study On The Content Of Rare Earth Elements In Tea In Mianyang City,Sichuan Province

Rare earth element is the lanthanides in the periodic table of chemical element – including 15 element named La,Ce,Pr,Nd,Pm,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu,and including 2 element named Y and Sc which is closely related to the lanthanides,so there are 17 elements in total.The ruthenium(Pm)element is radioactive and is produced artificially from fission of uranium,and does not exist alone in nature.With the increasing emphasis on food safety,in addition to common heavy metals such as cadmium(Cd),arsenic(As),mercury(Hg),chromium(Cr),and lead(Pb),the content of rare earth elements is also focused by public.Excessive rare earth elements have a great harm to the health.So we should increase the research on the content of rare earth elements.Tea is one of the most representative symbols of Chinese culture.China is the first country in the world to drink tea water.We have a long history of tea planting,exquisite tea-making skills and rich tea culture.Tea has become an indispensable necessity of life for the Chinese.Drinking tea is very beneficial to people's health.Tea is an important economic industry in China since ancient times,it is also an indispensable product in trade.Therefore,the quality and safety of tea is very important whether the people or the country.In recent years,China has more and more detection and research on heavy metal content and pesticide residues in tea.In this paper,the content of rare earth elements in tea in Mianyang City,Sichuan Province was studied by collecting tea samples for indoor analysis.From 2017 to 2018,a total of 80 tea samples were collected from the main tea-producing areas in Mianyang City,20 in Pingwu County and 20 in Beichuan County in 2017;20 in Pingwu County and 20 in Beichuan County in 2018.Inductively coupled plasma mass spectrometry(ICP-MS)was used to detect the content of rare earth elements in tea.The feasibility of ICP-MS for the determination of rare earth elements in tea was studied.The results shows that Inductively coupled plasma mass spectrometry(ICP-MS)is feasible,having low detection limit and high precision.At the same time,the content of rare earth elements in 80 tea samples from Mianyang City was analyzed.The results showed that:(1)The content of 16 rare earth elements in tea in Mianyang City was quite different,Ce?Y?Sc?La and Nd were the highest,and Ho?Tb?Tm and Lu were lower.The content of light rare earth is much higher than that of heavy rare earth,accounting for 70% of the total rare earth.(2)The total amount of rare earth oxides in 80 tea samples extracted from Mianyang City ranged from 205.08 to 1741.85 ?g/kg,with an average of 749.70 ?g/kg,which was lower than the total rare earth oxides in tea under national standard with limit quantity of 2mg/kg,it is in the safe range.(3)Among the two major tea-producing areas in Mianyang City,the total rare earth oxides in tea in Pingwu County and Beichuan County are within the same range and are similar.But the average total rare earth oxide in tea in Pingwu County is higher than the average rare earth in Beichuan County.The total amount of oxides may be related to the content of rare earth elements in the soil parent material of the tea garden,the geographical environment and climate in which the tea area is located,the different tea production and processing processes,the use of fertilizers and pesticides containing rare earths,environmental pollution,tea gardens.The acidification of the soil is related to the situation;(4)The total rare earth oxides of the tea samples taken in 2018 in Pingwu County and Beichuan County of the two major tea-producing areas are higher than the average rare earth oxides in the tea samples taken in 2017.The main results of this study provide a scientific basis for tea quality assessment in the tea-producing area of Mianyang City,Sichuan Province,and have certain guiding significance for the quality control of tea rare earth in the tea-producing area of Mianyang City.