title: Enantioselective degradation of (2RS,3RS)-paclobutrazol in peach and mandarin under field conditions.
abstract: In this study we investigated the enantioselective degradation of (2RS,3RS)-paclobutrazol in peach and mandarin fruits under field conditions after foliar treatment at 500 mg active ingredient/L using a Lux Cellulose-1 chiral column on a reverse-phase liquid chromatography-tandem mass spectrometry system. Degradations of paclobutrazol in both fruits followed first-order kinetics, with half-lives of about 9 days. Initial deposits were 1.63 mg/kg on peach and 1.99 mg/kg on mandarin; terminal concentrations were lower than 0.05 mg/kg, which was acceptable in most cases. As anticipated, paclobutrazol levels in peels of mature mandarin were about 6.3 times higher than in pulp, indicating the potential risk of peel consumption. We also observed that paclobutrazol degradation in mature mandarin was relatively slow, indicating it might not be efficient enough to hold mandarin fruits on trees for lowering paclobutrazol concentrations. Significant enantioselectivity was observed: the (2R,3R)-enantiomer was preferentially degraded in mandarin (whole fruit, peels, and pulp) but enriched in peach. Because of its more rapid degradation in mandarin and the lower levels observed in pulp compared with peels, potential endocrine-related side effects due to the (2R,3R)-enantiomer pose less of a risk in mandarin than in peach.
authors.affiliation: State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Quality and Standard on Agricultural Products, Zhejiang Academy of Agricultural Sciences, Hangzhou, People's Republic of China; Agricultural Ministry Key Laboratory for Pesticide Residue Detection, Institute of Quality and Standard on Agricultural Products, Zhejiang Academy of Agricultural Sciences, Hangzhou, People's Republic of China; Zhejiang Province Key Laboratory of Detection and Control for Pesticide Residues, Institute of Quality and Standard on Agricultural Products, Zhejiang Academy of Agricultural Sciences, Hangzhou, People's Republic of China.
authors.forename: Xiangyun
authors.initials: X
authors.lastname: Wang
authors.forename: Peipei
authors.initials: P
authors.lastname: Qi
authors.forename: Guiling
authors.initials: G
authors.lastname: Yang
authors.forename: Xinquan
authors.initials: X
authors.lastname: Wang
authors.forename: Hu
authors.initials: H
authors.lastname: Zhang
authors.forename: Hao
authors.initials: H
authors.lastname: Xu
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Wang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
mesh_terms: D002957:Citrus / Q000378:metabolism*; D005638:Fruit / Q000378:metabolism; D007700:Kinetics; D010573:Pesticide Residues / Q000737:chemistry* / Q000378:metabolism*; D027861:Prunus / Q000378:metabolism*; D013237:Stereoisomerism; D013379:Substrate Specificity; D014230:Triazoles / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D010573:Pesticide Residues; D014230:Triazoles; C053370:paclobutrazol
keywords: HPLC-MS/MS; enantioselective degradation; paclobutrazol; plant growth regulator