| Chinese tea culture has a long history.Tea is rich in polyphenols,alkaloids,vitamins and various mineral elements.In recent years,the concept that tea drinking is beneficial to health has been widely accepted.Sichuan Province is one of the main tea producing areas in the country.It has the characteristics of superior ecological conditions,rich varieties of tea trees,and profound tea culture.However,due to environmental pollution,tea will also be enriched in some harmful elements,such as plumbum(Pb),cadmium(Cd),chromium(Cr),arsenic(As)and other heavy metal elements.At the same time,explore such as potassium(K),calcium(Ca),magnesium(Mg),aluminum(Al),iron(Fe),manganese(Mn),zinc(Zn),copper(Cu),molybdenum(Mo),nickel(Ni),cobalt(Co),sodium(Na),tin(Sn),and vanadium(V)The tea species and the region where they are located are of great significance to the tea industry.At present,there are few reports on the distribution characteristics of the content of heavy metals and mineral elements in tea in Sichuan Province.Therefore,this project aims to establish an efficient,fast and accurate Inductively coupled plasma mass spectrometry(ICP-MS)method for the simultaneous determination of major heavy metals and mineral elements in tea.The investigation of the main heavy metals in tea and the exploration of the areas of high-quality mineral elements in tea in Sichuan Province will promote the rapid economic growth of Sichuan through the development of characteristic agricultural industries and satisfy the people’s continuous yearning for a better life.The method of using ICP-MS to simultaneously determine the heavy metal elements of Pb,Cr,Cd,As and the mineral elements of Ca,K,Mg,Na,Fe,Mn,Cu,Al,V,Co,Ni,Zn,Mo,Sn,R2 is equal Above 0.9990,the detection limit of each element is 0.004～0.80 mg/kg,the average value of the tea standard substance determination is within the confidence interval of the true value,the precision is less than 10%,and the recovery rate is within the range of93.6～102.6%.The result shows the accuracy and effectiveness of the method.Then use the established method to determine the heavy metal elements of Pb,Cr,Cd,As and Ca,K,Mg,Na,Fe,Mn,Cu,Al,V,Co,Ni,Zn,Mo,Sn in 242 batches of tea in Sichuan Province The results show that the average content of 4 heavy metals in a total of 242 batches of tea from15 regions in Sichuan Province is Cr > Pb > As > Cd,and the relationship of the coefficient of variation is Pb > Cr > As > Cd,where the coefficient of variation of Pb element is 56.1%,the coefficient of variation is the highest.The average content of mineral elements K > Ca >Mg > Mn > Al > Fe > Zn > Na > Cu > Ni > Co > V > Sn > Mo.The element content data of the sample was tested by k-s,and the elements Ca,K,Mg,Al,Ni,and Zn were normally distributed(P > 0.05).The green tea and scented tea in 242 batches of tea in Sichuan Province were screened for t-test or non-parametric test,and the K,Al,Zn,Mo,Pb,and Cr elements were significantly different(P < 0.05).Cluster analysis based on the average content of each element in tea from 15 cities can divide the 15 cities in Sichuan Province into four categories.The first category includes cities in Ganzi and Bazhong,and the second category includes Meishan,Guangyuan,and Guangyuan.Dazhou,Leshan,Ya’an,and Liangshan.The cities included in the third category include Zigong,Mianyang,Luzhou,Guang’an,Yibin,and Chengdu.The cities included in the fourth category include Nanchong.Taking tea in 5 cities in western Sichuan,4 cities in southern Sichuan,and 6 cities in northeastern Sichuan as the research objects,the overall distribution of heavy metals and mineral elements in the area was studied,and the differences of 18 elements between different tea types and cities were studied.,Perform principal component extraction and principal component comprehensive score calculation for the three areas.The results show that the content of heavy metals in the three areas is the same as that of the 242 batches of tea in Sichuan Province.The variation coefficients of Pb and Cr element content are higher than those of Cd and As.The mineral elements vary from area to area.According to the type of tea,each area showed that the content of K and Ni in green tea was higher than that in scented tea,and the content of Al in scented tea was higher than that in green tea.The main component analysis of the mineral elements extracted from the teas in West Sichuan,South Sichuan,and Northeast Sichuan respectively.K,Co,Ni,Zn,V,Cu,Fe,Na,Sn are the characteristic mineral elements in the 101 batches of tea in West Sichuan.It is calculated that the tea in Meishan and Ganzi cities has a strong ability to enrich mineral elements;Ca,Mn,Al,V,Ni,Cu,Fe,Mo are the characteristic mineral elements in 82 batches of tea in southern Sichuan,calculated by the comprehensive score of principal components Tea obtained from Gong and Luzhou cities has a strong ability to enrich mineral elements;K,Ni,Zn,Ca,Mg,Sn,and V are characteristic mineral elements in 59 batches of tea in northeastern Sichuan,and Guangyuan is calculated by the comprehensive score of principal components Tea from Mianyang and Mianyang have a strong ability to accumulate mineral elements.This paper uses the established ICP-MS method to analyze the heavy metal elements of Pb,Cr,Cd,As and Ca,K,Mg,Na,Fe,Mn,Cu,Al,V,Co,Ni,Zn,Mo,The detection of Sn mineral elements found that the average content of heavy metal Cr in tea in Sichuan Province was the highest,the coefficient of variation of heavy metal Pb was the largest,and the mineral elements Ni and V were characteristic elements.The average content of K and Ni in green tea was higher than the average in scented tea.The average content of Al in green tea is lower than the average content in scented tea.Tea from Meishan,Ganzi,Guangyuan,Mianyang,Zigong,and Luzhou has a strong overall distribution of mineral elements.It is of great significance for the monitoring of heavy metals in tea in Sichuan Province and the selection of tea areas with high mineral nutrition. |
