The Input Of 9,10-anthraquinone In Tea Cultivation And Processing

As a chemical material,9,10-anthraquinone?AQ?is used in paper-making and dyeing industry.In the agricultural,AQ was used as the bird repellent.Now AQ is never registered in our country.Due to the potential carcinogenicity,European Union set up the MRL of AQ 0.02 mg/kg in tea.In the other countries,there are not limit standard of AQ in tea.At present,the source of AQ in tea has been not clear.For the AQ present in the water and soil,it is necessary to clarify the possible sources in the tea cultivation.This study aims to identify the possible source of AQ,by developing the analytical methods to determine the AQ in fresh leaves,dry tea,tea brew,water and soil,and clearing the dissipation and transfer of AQ by simulated spray experiment,water and soil culture experiment.The contents and results of this study were as follows:?1?Established the analytical method of AQ in tea samples and environment samples.By optimizing the parameters of extraction and clean-up,the method by solvent extraction and GC-MS/MS determination was established for AQ detection.The recoveries for the AQ in matrix of tea,fresh leaves,tea brew,water and soil were in the range of 92.7%-111.5%,87.0%-110.8%,106.9%-116.2%,89.7%-119.6%and 75.8%-111.0%,respectively,with RSDs less than 17.0%.The LOQs of AQ in tea,leaves,tea brew,water and soil were 0.01 mg/kg,0.01 mg/kg,0.4?g/L,0.01 mg/kg,and 1.0?g/L,respectively.The matrix effects were-9.8%?-7.0%?-29.9%?-24.4%?-17.6%,respectively,respectively.The developed method fulfills the requirement of AQ detection.?2?The transfer of AQ during tea cultivation-tea processing-tea brewing was investigated.The AQ dissipation followed the first-order kinetics,the kinetic regression curve of AQ was C_t=1.0261e^-0.1893t?r²=0.8099?with half-live of 3.7 days.In the tea processing,the residues of AQ on fresh leaves were partly dissipated and the total loss were 63.0%-82.9%and 58.8%-84.6%in the black tea and green tea,respectively.Among all the steps in manufacture,the drying step was mainly responsible for AQ dissipation.The brewing efficiency of AQ from made tea to tea brew was about 10%.Although the AQ level decreased in tea cultivation and tea processing,the AQ in dry tea would excess MRL 0.02 mg/kg if the AQ in fresh leave was higher than 0.024 mg/kg.Therefore,the deposition of AQ on fresh leaves might one of the reasons resulted in AQ contamination in tea.?3?9,10-anthraquinone transfers and distributes in tea plant during the water cultivation.Considering the hydrolytic behavior of AQ in the water cultural and distilled water,it is confirmed that AQ degraded rapidly in water,which followed the first-order kinetics,the kinetic regression curve of AQ was C_t=0.3344e^-0.451t?r²=0.8519?and C_t=0.388e^-0.235t?r²=0.9239?with half-live of 1.5 and 3.0 days in water culture and distilled water,respectively,in which the mineral salt could accelerate the degradation of AQ in water.So the tender leaves,mature leaves,roots and water were detected which were added at the series dosage from 0.025 mg/L to 1.0 mg/L and plucked randomly at 0?2 h?,1,2,5,7,10,15,20,30,50 days by the changing the hydroponics nutrient solution of AQ everyday.It was observed that the root had an obvious absorptive activity with the enrichment factor from 20 to 90.Research indicated that the AQ could transfer upward from roots to leaves,and the translocation factor of AQ was 0.02%-3.5%.The AQ level in mature leaves was more than that in the tender leaves.As when the concentration of AQ in tender leaves was higher than 0.024 mg/kg,which occurred when the AQ added in water was more than 0.25 mg/L,the AQ in the dry tea after the manufacture process would be higher than the MRL of AQ 0.02 mg/kg establishing in EU.Therefore,the AQ in water might be one of the reasons resulted in AQ contamination in tea.?4?9,10-anthraquinone transfers and distributes in tea plant in the soil cultivation.The leaves,roots and soil samples were collected and detected on days 1,3,7,30,85,145,165,195 after the AQ was added in soil at the dosage from 0.5 mg/kg to 5.0 mg/kg.Research showed that the AQ was unmobile in soil.AQ could be absorbed by root in lesser degrade,however the AQ located in roots was difficult to transfer to the leaves.So,it was less likely to contaminate the tea when the AQ was present in soil.In conclusion,the AQ deposit in environment could cause the contamination of AQ in made tea.The level of AQ was more than the MRL 0.02 mg/kg when the concentrations of AQ in tender leaves were more than 0.024 mg/kg.The presence of AQ in water could result the exceeding of AQ in made tea,when the addition concentration of AQ was higher than 0.25 mg/L.AQ was hardly transferred from soil to leaves.So,the deposit of AQ could be one of the the reasons that resulted in AQ contamination in tea during the cultivation.