New Progress in the Study of Enantiomeric Residues of Novel Chiral Pesticides

The rational application of chemical pesticides is one of the effective measures for controlling pests and diseases in tea plantations. Assessing the degradation and metabolic risks of pesticide residues after application helps ensure the quality and safety of tea, promoting the healthy development of the tea industry. Establishing efficient, sensitive, and universal analytical methods for chiral pesticide enantiomer residues is key to ensuring the safety of such residues in tea plantations.

Recently, the Tea Pest and Disease Control Innovation Team at the Tea Research Institute of the Chinese Academy of Agricultural Sciences has made new progress in chromatographic separation research of enantiomers of novel chiral pesticides. Their findings, titled “A novel ‘mobile phase braking drift technique’ utilized for the enantioselective residual analysis of cyflumetofen and the investigation of its enantiomeric migration during tea growth, processing, and brewing,” were published as a supplementary cover article in the internationally renowned journal Journal of Agricultural and Food Chemistry.

Key Findings of the Study

• This study is the first to achieve the enantiomeric separation of Cyflumetofen (CYF) using reversed-phase liquid chromatography (RP-LC).
• An enantioselective residue analysis method was established using reversed-phase ultra-high performance liquid chromatography coupled with tandem mass spectrometry (RP-UHPLC-MS/MS).
• The migration behavior of CYF enantiomers during tea plant growth, processing, and brewing was investigated in detail.
• The limits of quantification (LOQs) for CYF enantiomers in fresh tea leaves, processed tea, and tea infusion were 2.5 μg/kg and 0.25 μg/L, respectively.
• During tea plant growth, the half-lives of (+)-CYF and (−)-CYF were 1.04 days and 1.23 days, respectively.
• During processing, processing factors (PFs) and migration rates of the enantiomers were calculated. There was no significant enantioselective degradation (EF ≈ 0.5).

Link to the original article: https://pubs.acs.org/doi/abs/10.1021/acs.jafc.5c00891

The responsible use of chemical pesticides is essential for managing pests in tea plantations. However, ensuring tea safety and quality requires understanding how pesticide residues degrade and migrate. A recent study led by the Tea Research Institute of the Chinese Academy of Agricultural Sciences has made a significant breakthrough in the enantioselective analysis of Cyflumetofen (CYF), a novel chiral pesticide with potential application against mites in tea crops.

A New Method for Enantiomer Separation

Researchers developed an innovative “mobile phase braking drift technique” that successfully separated CYF enantiomers using reversed-phase liquid chromatography (RP-LC)—a first in the field. This method resolves the limitations of previous techniques that lacked compatibility with mass spectrometry and had low sensitivity.

Advanced Analytical Technique

The team established a highly sensitive RP-UHPLC-MS/MS method for detecting and quantifying CYF enantiomers and their metabolites in tea leaves, processed tea, and tea infusion. The method includes:

• LOQs of 2.5 μg/kg in tea leaves and 0.25 μg/L in tea infusion
• High compatibility with mass spectrometry
• Improved accuracy in chiral pesticide residue analysis

Behavior of Enantiomers in the Tea Lifecycle

The study explored the enantiomeric migration of CYF throughout the entire lifecycle of tea:

• Half-life during growth: (+)-CYF = 1.04 days, (−)-CYF = 1.23 days
• Processing and brewing: Minimal enantioselective behavior (EF ≈ 0.5)
• Leaching and residue risks remained within acceptable safety limits

Researchers and Support

The first author of the paper is Ning Yating, a 2024 graduate student at the Tea Research Institute. Prof. Zhang Xinzhong and Prof. Chen Liezong served as corresponding authors. The work was supported by:

• National Key Laboratory of Agricultural Product Quality and Safety Risk Prevention and Control (Zhejiang)
• National Natural Science Foundation of China
• Innovation Project of the Chinese Academy of Agricultural Sciences