Detection Of Pesticides Residue And Mycotoxins In Traditional Herbal Tea By Dispersed Liquid-liquid Microextraction

China plants and exports most herbal medicines in the world,having a rich and profound culture of traditional Chinese medicines and Chinese herbal tea.At present,organophosphorus,organochlorine and pyrethroid pesticides with the highest detection rate in traditional Chinese medicine.At the same time,the management and residue standards of pesticides in traditional Chinese medicines are still inadequate in our country,which easily leads to excessive residues of pesticides in traditional Chinese medicines and products.In addition,Chinese herbal medicines are also susceptible to fungal infection in the process of cultivation,transportation and storage,meanwhile under suitable environmental conitions some fungi could produce secondary metabolites mycotoxins,such as aflatoxins,which are harmful to human beings and livestocks.Chinese herbal medicine is the main material of Chinese herbal tea,therefore,the Chinese herbal tea will inevitably be contaminated by mycotoxins and pesticides,thus endangering the health of consumers,causing losses to the economic benefits of herbal tea,and restricting the export of Chinese herbal medicine products.At present,there is no detection method of pesticides and mycotoxins in Chinese herbal tea,and there is a lack of understanding of the pollution of harmful substances in Chinese herbal tea.Therefore,it is necessary to develop a rapid,sensitive analytical technique for the simultaneous determination of mycotoxins and pesticides in Chinese herbal tea.which is of great significance to ensure the quality and safety of Chinese herbal tea.Based on a simple,rapid,high enrichment ratio and good environmental compatibility sample pretreatment technology-dispersion liquid-liquid microextraction technology(dispersive liquid-liquid microextraction,DLLME),combined with chromatography-mass spectrometry analysis,the determination of pesticide residues and aflatoxin in Chinese herbal tea was studied.The results are as follows:A new vortex-assisted DLLME technique was developed to determine organophosphorus pesticide and aflatoxins residues in Chinese herbal tea beverages by ultrahigh performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).Based on the central combination design response surface method,the important parameters affecting extraction recovery were optimized,the interaction among variables was researched,and the best experimental combination was obtained.The optimum conditions are as follows: 5 m L Chinese herbal tea sample(p H 5.1),chloroform as extraction solvent,347 ?L in volume,acetonitrile as dispersive solvent and 1614 ?L in volume.Under the optimum conditions,the linear range of each target was 0.1-25 ?g/L,the correlation coefficient(R²)was > 0.9980,and the limits of quantitative(LOQ)for target pesticides and aflatoxins were 1 ?g/L and 0.2 ?g/L,respectively.The recovery of target compounds were between 70.06% and 115.65%,the relative standard deviation(RSDs)was less than 8.54%(n=5),and the enrichment multiple was 25 times.The established method was applied to ten batches of actual samples.The results showed that Phoxim and chlorpyrifos were detected in a batch of Chinese herbal tea samples at low concentrations of 1.6×10^-4mg/kg and 1.0×10^-4 mg/kg,respectively.The residues of phoxim and chlorpyrifos were 0.01 mg/kg and 0.02 mg/kg respectively,which were lower than the maximum residue limit(MRL)of Chinese herbal medicines established by European Union.A method for the determination of organochlorine pesticide residues in Chinese herbal tea beverages by ultrasound-assisted DLLME combined with GC-ECD was established.The response surface method(RSM)based on the central composite design was used to optimize the important parameters affecting the extraction recovery rate,and the interaction between the variables was determined to obtain the best experimental combination.The optimum conditions were as follows: p H value of 5 m L Chinese herbal tea solution is 3.1,salt concentration is 16.10%,extractant is 1-undecanol,volume is 72 ?L,dispersant is ethanol,volume is 399 ?L.Under the optimum conditions,the linear range(0.01 mg/L-5 mg/L)of each target has a good linear relationship,and the correlation coefficient(R²)is higher than 0.9980.The limit of quantitation(LOQ)of each target pesticide was 5×10-3mg/L.and the recovery ranged from 76.18% to 107.48%,relative standard deviation(RSDs)was less than 7.47%(n = 5),and enrichment multiple was between 78 and 91.An ultrasonic assisted temperature control combined with DLLME pretreatment technique was established to determine five pyrethroid pesticides in Chinese herbal tea drinks by HPLC-DAD.The response surface optimization design method was used to optimize the important parameters affecting the extraction recovery.the interaction between the variables was determined and the best experimental combination was obtained.The optimum conditions were as follows: sample p H value is 2.9,ionic liquid is [HMIMPF₆],volume is 121 ?L,dispersant is acetonitrile,volume is 794 ?L,heating temperature is 38.8 C,ultrasonic time is 3.6 min,In the range of 0.05 mg/L-5 mg/L,the linearity of each target was good,and the correlation coefficient(R²)was higher than 0.9990.The limit of quantitation(LOQ)was 5×10^-3 mg /L.The average recovery of targets ranged from 74.02% to 109.01%,and the relative standard deviation(RSDs)ranged from 3.41% to 9.04%(n=5).The concentration multiple is 37-40 times.The proposed method is simple,rapid,sensitive and environmentally compatible.It can be used for the determination of trace pyrethroid pesticides in practical samples.