OMB First to Final Action Recommendation Checklist 11-12-18

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Conclusions

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In summary, the degradation regularity of 271 pesticides in aged Oolong tea over 120 days was studied by the developed GC-MS/MS method. The results indicate that >70 of the 271 pesticides decreased exponentially or logarithmically in aged Oolong tea, con¿rming that the pesticides in aged Oolong tea degrade slowly and the concentrations of pesticides decrease with the increase of time intervals over 4 months. Further discussion of the different classes of pesticides suggests that most of the organophosphorus pesticides degraded in accordance with degradation trends A and B in aged Oolong tea and that most of the organochlorine pesticides decreased according to degradation trend E in aged Oolong tea. The pesticide residues in aged Oolong tea were predicted accurately by subtracting the degradation value of target pesticides on a speci¿c day from the logarithmical curves, generated by plotting determination time (day) and the difference between each measured value and ¿rst-time-measured value of target pesticides on the x - and y -axes, respectively. The predicted results of 14 pesticides were satisfactory by comparing them with measured results at one of the concentrations of the Youden pair. It is our hope that the obtained degradation regularity of 271 pesticides in aged Oolong tea will be helpful for studying the stability of standard material of multipesticide residues in tea. In addition, we propose that the prediction procedure of pesticides in aged Oolong tea in the present study may offer a new method for the error analysis of multiresidue of pesticides in other complex matrixes of international, interlaboratory study.

Acknowledgments

This work was ¿nancially supported by the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China (AQSIQ) special public welfare project of China (Project No. 201010080).

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