Journal of Oleo Science Copyright ©2017 by Japan Oil Chemists’ Society doi : 10.5650/jos.ess16230 J. Oleo Sci. 66, (6) 623-632 (2017) Highly Selective and Considerable Subcritical Butane Extraction to Separate Abamectin in Green Tea Yating Zhang1, Lingbiao Gu1, Fei Wang2, Lingjun Kong1, Huili Pang1 and Guangyong Qin1＊ 1 School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, CHINA 2 School of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, CHINA Abstract: We specially carried out the subcritical butane extraction to separate abamectin from tea leaves. Four parameters, such as extraction temperature, extraction time, number of extraction cycles, and solid– liquid ratio were studied and optimized through the response surface methodology with design matrix developed by Box–Behnken. Seventeen experiments with three various factors and three variable levels were employed to investigate the effect of these parameters on the extraction of abamectin. Besides, catechins, theanine, caffeine, and aroma components were determined by both high-performance liquid chromatography and gas chromatography–mass spectrometry to evaluate the tea quality before and after the extraction. The results showed that the extraction temperature was the uppermost parameter compared with others. The optimal extraction conditions selected as follows: extraction temperature, 42℃; number of extraction cycles and extraction time, 1 and 30 min, respectively; and solid–liquid ratio, 1:10. Based on the above study, the separation efficiency of abamectin was up to 93.95%. It is notable that there has a quite low loss rate, including the negligible damage of aroma components, the bits reduce of catechins within the range of 0.7%–13.1%, and a handful lessen of caffeine and theanine of 1.81% and 2.6%, respectively. The proposed method suggested subcritical butane possesses solubility for lipid–soluble pesticides, and since most of the pesticides are attached to the surfaces of tea, thus the as-applied method was successfully effective to separate abamectin because of the so practical and promising method. Key words: subcritical butane extraction, response surface methodolog, abamectin 1 Introduction treat parasitic worms in vegetables, fruit trees, cottons and Tea, along with coffee and cocoa, belongs to the three flowers6）. Moreover, abamectin is also classified as one of leading beverages in the world. Tea leaf contains a unique the highly toxic compounds by the World Health Organiza- series of natural chemicals, such as tea polyphenols, alka- tion. So, it has a negative impact on the environment and loid, vitamins, protein, and amino acid1）. These nutrient organisms. Besides, abamectin can be transferred to organ- and medical components may help people fight with isms through the food chain and then affect the health of cancer, decrease cholesterol, resist radiation and ageing, human beings7）. promote digestion, and so on2）. So far, China has steadily A variety of reports have been published about the been the largest producer of tea in the world, and it has testing techniques of pesticide residues in tea8）. However, become the mainspring to drive the global growth of tea only few report on the separation or extraction of these production3）. Unfortunately, the export decreased in recent residues. Current approaches to separate such materials years, because of the pesticide residues in tea4）. Thus, from plants include hydrostatic pressure9）, microbial deg- more attention should be paid to the quality and safety of radation10）, ultraviolet degradation11）, ozonation degrada- tea5）. tion12）, and chemical degradation13）. For instance, sodium Abamectin, a novel and efficient biological pesticide, carbonate can facilitate the degradation of organophospho- separated from streptomyces avermitilis, is widely used to rus pesticides14）. A study by Wu and coworkers15）indicated ＊Correspondence to: Guangyong Qin, School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, CHINA E-mail: [email protected] Accepted February 6, 2017 (received for review December 9, 2016) Journal of Oleo Science ISSN 1345-8957 print / ISSN 1347-3352 online http://www.jstage.jst.go.jp/browse/jos/ http://mc.manusriptcentral.com/jjocs 623 Y. Zhang, L. Gu and F. Wang et al. that the degradation of pyrethroid in tea increased when ising for extracting trace amounts of pesticide from nature the dose of irradiation was raised. Zhan & Tian16）found that plants. the captan in apples decreased gradually along with in- creasing the ozone concentration, treatment time, and re- action temperature. So the optimal technological condi- tions of degradation are as follows: the initial concentration 2 Materials and methods of ozone should be 6 mg/L, pH 11, reaction temperature 2.1 Sample 40℃, and reaction time 30 min. However, when consider- The tea leaves used in this study were picked from the ing the low degradation efficiency and limited processing tea plantation. In experimental processes, the working conditions, these methods were not widely acceptance. concentration of abamectin（100 g/L, Huozhou Oasis Chem- Since 1980s, supercritical fluid extraction（SFE）was uti- icals Co., LTD., in July 2014）was adjusted to twice the sug- lized to remove pesticide residue from plants. While the gested value. Three days after spraying the pesticide on supercritical fluid of CO2 was used to extract pesticide the tea trees, the tea leaves located at the top of the residue from plants at different pressures and tempera- branches were picked and then stir fried, then transferred tures17）. Moreover, accelerated solvent extraction（ASE） to our laboratory within the same day at a temperature of was used to rapidly detect the contents of organochlorine 4℃. and organophosphorus on tea leaves18, 19）. However, no matter SFE or ASE can cause a certain degree of damage 2.2 Apparatus to the plant samples. To make matters worse, both tech- Extractions were performed via a subcritical Fluid Ex- niques require a high working pressure, in the range of traction System（CBE-5L, Henan Subcritical Biological 7-50 Mpa20, 21）, which can deal with only small sample quan- Technology Co., Ltd., Anyang, China）. Abamectin in green tities, thereby preventing large-scale industrial application. tea was determined through an LC-MS/MS（Agilent1200/ Humbert and co-workers22）coupled ion-exchange resin and API4000, Santa Clara, California, USA）. The chromato- activated carbon to remove pesticide residue and insoluble graphic analysis of tea aroma components was conducted organic chemicals from plants. Despite attaining high using a GC-MS（Agilent 7890-5795, Santa Clara, California, removal efficiency, this approach is so complicated that it USA）. The dried tea samples were ground successively has strict requirements regarding the sample’s shape. It is with a herbal medicine grinder（DJ-04B, Dianjiu Traditional therefore not suitable for tasks in which the original shape Chinese Medicine Machinery Manufacturing Co. Ltd, of the tea leaves needs to be retained. Fortunately, the China）, an ultrasonic cleaner（KH-500DE, Huyueming Sci- emergence of subcritical fluid extraction technology solved entific Instrument Co. Ltd., China）, a rotary evaporator a series of problems. This technique uses a green organic （R-210, Buchi, Switzerland）, a high-speed refrigerated solvent. It is relatively simple and rapid, and demands centrifuge（3K15, Steinheim, Germany）, and a vortex mixer fewer instrumental devices than any other methods, （VX200, Labnet, NJ, USA）. because it takes the advantages of low pressure（0.2～0.6 MPa）and temperature（0～60℃）, high extraction efficien- 2.3 Reagent cy, suitability for loop extraction, ease of operation, low Acetonitrile, methanol, acetone, ethyl acetate, butane, energy consumption, and scalability for large-scale indus- hexane, etc., were of chromatographic grade and pur- trial extractions when compared with other extraction chased from J. T. Baker（NJ, USA）. Anhydrous magnesium techniques. So it has been recognized, applied, and prac- sulfate, sodium chloride, citric acid, and sodium citrate ticed in large-scale industrial productions. Currently, it is dibasic sesquihydrate were of analytical grade and acquired mostly used for extracting flavors and fragrances23, 24）, es- from the North Reagent Company（Tianjin, China）. A salt- pecially for functional edible oils25）, natural pigments26）, ing-out reagent kit（Supelco, PA, USA）was used consisting and medicinal compositions27）. of 4 g anhydrous magnesium sulfate, 1 g sodium chloride, 1 In this study, abamectin was separated by a subcritical g sodium citrate, and 0.5 g sodium citrate dibasic. Primary– fluid with butane as solvent. The extraction conditions secondary amine（PSA）sorbent was purchased from were surveyed with a three-variable, three-level experi- Supelco（PA, USA）. Water（18.2 MΩ cm）was purified using ment designed by Box–Behnken, which was based on the Milli-Q system equipment（Billerica, MA, USA）. response surface methodology（RSM）. The separation effi- ciency of abamectin were assessed by high-performance 2.4 Standard substances liquid chromatography（HPLC）tandem mass spectrometry Abamectin（≥ 99％）, phenethyl acetate（≥ 99％）, and （LC-MS/MS）analysis. Finally, the catechins, caffeine, the- isazofos（≥ 95％）were purchased from Dr. Ehrenstorfer anine, and main aroma components were analyzed by Company（Germany）. Six kinds of catechins, caffeine, and HPLC and GC-MS. The results demonstrated that the sub- theanine were received from Aladdin Company（Shanghai,