Accumulation And Opitmal Design For Determination Of Fluoride In Camellia Sinensis (L.)O. Kuntze

Tea plants are hyper-accumulators of fluoride, and quantities of fluoride accumulatedin the tea plants was20～30times higher than that in other plants. Proper contents offluoride in human body were good to health, but excessive fluoride resulted in chronicfluorosis, which was known as dental fluorosis and skeletal fluorosis. Therefore, it wasimportant to determinate the rules of fluoride accumulated in tea plants and the factorsinfluencing it. In this paper, the different methods for extracting fluoride from tea werecompared, and the potentiometric methods for determining fluoride in tea liquid wereoptimized. Impacts of different Al concentrations and Al/F ratios on the uptake andtranslocation of fluoride in tea plants were examined under the controlled condition inthe lab. The effects of anionic channel inhibitor, cation ion channel inhibitor and waterchannel inhibitor on the accumulation of fluoride in tea plants were also analyzed. Theresults revealed that:1. The recoveries of the boiling water extraction method （93.17%） were higher thanthat of the shaking extraction in acidic water （68.19%） and the ultrasonic extraction（62.38%）. In this paper, the linear range of potentiometric determination of fluoride in teawas between30and200mg/kg, the mean recovery was90.48%with the square of thecorrelation coefficient （R²） of0.9922. The limit of quantification （LOQ） and limit ofdetection （LOD） were54mg/kg and18mg/kg respectively. The fluoride contents in fourtea samples from Anhui province were ranged from49.62mg/kg to73.8mg/kg,and thefluoride components in spring tea were lower than that in autumn tea, and both of themwere lower than that of the national standard of fluoride in tea （200mg/kg）.The resultsprovide reliable methods for rapid determination and quality assessment of fluoride in tea.2. The quantities of fluoride accumulated in tea plants were increased under thelow Al³⁺concentrations （20,40and67mg/L）, most of the fluoride absorbed in teaplants were in ionic forms. While the amounts of fluoride accumulated in tea plantswere declined under the high Al³⁺concentrations （100,200,400and600mg/L）, andmost of the fluoride absorbed in tea plants were in the Al/F chalator. The amounts offluoride accumulated in tea leaves were increased after different concentrations of Alamended in solution. The amount of F accumulated in tea plants were inhibited whenthe ratios of Al/F in solution were higher than1, but it was promoted as the ratios ofAl/F in solution were lower than1. Aluminum can accelerate fluoride translocation from roots to leaves in tea plants. The high translocation factors were found in teaplant when fluoride in AlF₂⁺, AlF₃and AlF₂^-forms.3. There were no significant differences on the effects of0.5,2.0and10.0mg/Lwater channel inhibitors （HgCl2） on the quantities of fluoride absorbed in tea roots andaccumulated in above ground parts of tea plants. Quantities of fluoride accumulatedin tea plants were inhibited under the anionic channel inhibitors （10μmol/L,20μmol/Land100μmol/L NPPB）, but NPPB can accelerate fluoride translocation from roots toleaves in tea plants. Amounts of fluoride up-taken in tea roots and accumulated in teaplants was significant （P<1%） lower that in the control treatments under the10μmol/L ofNPPB concentration. Amounts of fluoride accumulated in tea plants were inhibitedunder the anionic channel inhibitors （10,20μmol/L DIDS）. Moreover, quantities offluoride up-taken in tea roots and accumulated in tea plants was significant lower thanthat in the control treatment （P<1%） under the20μmol/L of DIDS concentration. Thereis no difference on quantities of fluoride accumulated in tea plants under the treatmentof the cationic channel inhibitors. Quantities of AlF₂⁺（Al/F1:2）accumulated in teaplants were inhibited and quantities of AlF₂⁺（Al/F1:1）accumulated in tea plants wasnot significant inhibited under the cationic channel inhibitors.