Application and enantiomeric residue determination of diniconazole in tea and grape and apple by supercritical fluid chromatography coupled with quadrupole-time-of-flight mass spectrometry
Application and enantiomeric residue determination of diniconazole in tea and grape and apple by supercritical fluid chromatography coupled with quadrupole-time-of-flight mass spectrometry
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超临界流体色谱-四极杆飞行时间质谱法测定茶叶、葡萄、苹果中烯效唑的应用及对映体残留
DOI：
10.1016/j.chroma.2018.10.051
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发表时间：
2018-12-21
影响因子：
4.1
通讯作者：
Luo Fengjian
中科院分区：
文献类型：
--
作者：
Zhang Xinzhong;Zhao Yuechen;Luo Fengjian
建立了超临界流体色谱-四极杆飞行时间质谱联用（SFC-Q-TOF/MS）法分离和测定茶叶、苹果和葡萄中烯唑醇对映体的方法。采用Chiral CCA色谱柱分离烯唑醇对映体，并对色谱条件（移动的比例、流动相、柱温、反压、助溶剂）进行了优化。选择了CO2/异丙醇（IPA）为移动的流动相的SFC-Q-TOF/MS最佳条件。（v/v，96/4），流速为2.0 mL/min，自动背压调节器（ABPR）为2000 psi，柱温为25 ℃，电喷雾正离子模式，最佳辅助溶剂为2 mmol/L乙酸铵的甲醇/水溶液（v/v，1/1）。茶叶和水果样品中6种农药残留采用乙腈/水（体积比，水果为4/1，茶叶为2/1）提取，经Cleanert TPT或Pesti-Carb固相萃取柱净化后，采用SFC-Q-TOF/MS基质匹配外标法定量。烯唑醇对映体在CCA柱上的洗脱顺序为R-（-）-烯唑醇优先，S-（+）-烯唑醇次之。样品中R-（-）-烯唑醇和S-（+）-烯唑醇的标准曲线浓度水平范围为0.01 mg/L至1.00 mg/L，相关系数大于0.99。在0.005、0.05和0.25 mg/kg 3个水平下，R-烯唑醇和S-烯唑醇在苹果和葡萄中的加标回收率为69.8%~ 102.1%，相对标准偏差（n = 6）为3.5%~ 10.4%，定量限（LOQ）均低于0.005 mg/kg。红茶中0.01、0.10和0.50 mg/kg 3个水平的加标回收率在85.6%~ 90.6%之间，RSD（n = 6）在3.9%~ 9.5%之间，定量限为0.01 mg/kg。该方法简便、可靠，能满足苹果、葡萄和茶叶中烯唑醇对映体的残留分析要求。并应用于R-（-）-烯唑醇和S-（+）-烯唑醇在茶叶鲜叶生长、绿色茶和红茶加工过程中的残留动态研究。R-（-）-烯唑醇和S-（+）-烯唑醇在茶树鲜叶中的降解半衰期（DT 50）分别为2.9 d和3.1 d。R-（-）-烯唑醇和S-（+）-烯唑醇的浓度随时间的延长而逐渐降低，在施药后第14天均低于初始浓度的10%。R-（-）-烯唑醇和S-（+）-烯唑醇在鲜茶叶中施用后2 h、2、5、7、10和14 d的平均对映体分数（EF）分别为0.505、0.526、0.523、0.558、0.453和0.489。这一结果与我们对另一种三唑类杀菌剂顺式氟环唑对映体在鲜茶叶中残留的研究结果相似。在整个红茶加工过程中，R-（-）-烯唑醇和S-（+）-烯唑醇分别下降了37.1%~ 49.3%和35.9%~ 57.9%。R-（-）-烯唑醇和S-（+）-烯唑醇对红茶加工的总加工因子（PF）分别为0.507-0.629和0.421-0.641。R-（-）-烯唑醇和S-（+）-烯唑醇在红茶加工中的EF值在0.432 ~ 0.532之间。而在整个绿色茶加工过程中，R-（-）-烯唑醇和S-（+）-烯唑醇分别下降了22.3%~ 32.6%和21.7%~ 40.3%，红茶与绿色茶相差近15%，且在绿色茶中下降幅度小于红茶。R-（-）-烯唑醇和S-（+）-烯唑醇在绿色茶中的总PF分别为0.674-0.777和0.597-0.783。R-（-）-烯唑醇和S-（+）-烯唑醇在绿色茶加工中的EFs范围为0.473 ~ 0.504。研究结果表明，对于R-（-）-烯唑醇和S-（+）烯唑醇的减少，在红茶加工中，揉捻和发酵是关键步骤，而在绿色茶加工中，揉捻是关键步骤。(C)2018 Elsevier B. V.版权所有。
A chiral separation and residue determination method for diniconazole enantiomers in tea, apple, and grape was developed and validated by supercritical fluid chromatography coupled with quadrupole time-of-flight mass spectrometry (SFC-Q-TOF/MS). The two diniconazole enantiomers were separated on a Chiral CCA column, and the chromatographic conditions (mobile phase proportion and modifier, column temperature, backpressure, and auxiliary solvent) were optimized. The optimal SFC-Q-TOF/MS conditions were selected as a mobile phase of CO2/isopropanol (IPA) (v/v, 96/4), flow rate at 2.0 mL/min, automated back pressure regulator (ABPR) at 2000 psi, column temperature at 25 degrees and under electrospray ionization positive mode with the best auxiliary solvent of 2 mmol/L ammonium acetate in methanol/water (v/v, 1/1) at 0.20 mL/min flow rate. Residues in tea and fruit samples were extracted by acetonitrile/water (v/v, 4/1 for fruit and 2/1 for tea), purified by Cleanert TPT or Pesti-Carb solid phase extraction column, then analyzed by SFC-Q-TOF/MS with matrix-matched external standard quantification method. The elution order of diniconazole enantiomers on CCA column was R-(-)-diniconazole at first, and S-(+)-diniconazole at second. The standard curve concentration levels of R-(-)-diniconazole and S-(+)-diniconazole in samples ranged from 0.01 mg/L to 1.00 mg/L with the correlation coefficients greater than 0.99. The spiked recoveries of R-(-)-diniconazole and S-(+)-diniconazole in apple and grape at three levels of 0.005, 0.05 and 0.25 mg/kg were in the range of 69.8% to 102.1%, with relative standard deviations (RSDs) (n = 6) between 3.5% and 10.4%, and the limits of quantitation (LOQs) below 0.005 mg/kg. The spiked recoveries in black tea at three levels of 0.01, 0.10, and 0.50 mg/kg were in the range of 85.6% to 90.6%, with the RSDs (n = 6) ranging from 3.9% to 9.5%, and LOQ of 0.01 mg/kg. This residue analysis and determination method for diniconazole enantiomers in apple, grape and tea samples is convenient, reliable, and meets the residue analysis requirement. Also it is applicatied for the residue fates of R-(-)-diniconazole and S-(+)-diniconazole during the fresh tea leaves growing, green tea processing and black tea processing. The degradation half-times (DT50) between R-(-)-diniconazole and S-(+)-diniconazole in the fresh tea leaves growing were 2.9 d and 3.1 d, respectively. The concentrations of R-(-)-diniconazole and S-(+)-diniconazole decreased gradually with time and on the 14th day after application were lower than 10% of the initial concentration. The average enantiomer fractions (EFs) of R-(-)-diniconazole and S-(+)-diniconazole at 2 h, 2, 5, 7, 10 and 14 d after application in fresh tea leaves were 0.505, 0.526, 0.523, 0.558, 0.453 and 0.489, respectively. This result is similar to the result of our last research for the enantiomers of cis-epoxiconazole-another triazole fungicide residues in fresh tea leaves. And in the whole black tea processing, 37.1%-49.3% and 35.9%-57.9% of R-(-)-diniconazole and S-(+)-diniconazole decreased, respectively. The total processing factors (PFs) of R-(-)-diniconazole and S-(+)-diniconazole for the black tea procedure were 0.507-0.629 and 0.421-0.641, respectively. The EFs of R-(-)-diniconazole and S-(+)-diniconazole in black tea processing ranged from 0.432 to 0.532. However, in the whole green tea processing, 22.3%-32.6% and 21.7%-40.3% of R-(-)-diniconazole and S-(+)-diniconazole decreased, respectively.The difference between black tea and green tea is nearly 15%, and in green tea is less decreased than in black tea. The total PFs of R-(-)-diniconazole and S-(+)-diniconazole for the green tea procedure were 0.674-0.777 and 0.597-0.783, respectively. The EFs of R-(-)-diniconazole and S-(+)-diniconazole in green tea processing ranged from 0.473 to 0.504. The PFs illustrated that for R-(-)-diniconazole and S-(+)diniconazole decrease, the rolling and fermentation were the critical steps in black tea processing, and the rolling was the critical step in green tea processing, respectively. (C) 2018 Elsevier B.V. All rights reserved.