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RATIONALE For the risk assessment of penconazole in the environment and the evaluation of the possible consequences of its use, it is important to determine how its reactivity and degradation are influenced by metals commonly found in nature, such as copper and zinc. METHODS Changes in the reactivity of penconazole in the presence of zinc/copper ions were studied using electrospray ionisation mass spectrometry and density functional theory calculations. RESULTS Many penconazole complexes with copper and zinc ions were created; a comparison of the elements showed that a few complexes were formed analogously (doubly charged complexes with four penconazole molecules, singly charged complexes with chlorine as a counterion and singly charged complexes with deprotonated penconazole as a counterion). The metal complexes with different structures indicated different reactivity of penconazole with copper and zinc. CONCLUSIONS The experimental and computational approaches have revealed different changes in the structure of penconazole. In the Zn(II) complex, penconazole deprotonated to stabilise the bond to Zn(II). In the Cu(II) complex, it loses one chlorine atom, creates an additional ring between the triazole ring and the phenyl ring, and/or creates a double bond in the short aliphatic chain.

RATIONALE Frequently used pesticide cyproconazole (Cyp) interacts with essential elements commonly present in soil and playing important roles in various enzymatic processes. These interactions predetermine Cyp degradation pathways. We suggest a simple experimental and theoretical approach for the prediction of pesticides behavior. METHODS Cu/Cyp complexes are explored because of the typical Cu(II) reduction in complexes. Its level and the stability of Cu-ligand bond depend on the type and the number of the surrounding ligands. Zn/Cyp complexes were compared as it is not expected that Zn(II) will reduce. The complexations were studied by means of electrospray ionization ion trap mass spectrometry and MS/MS collision induced dissociations with comparative and explicative density functional theory calculations. RESULTS Cyp ligand allows both, Cu(II) reduction as well as, in specific cases, it protects the higher Cu oxidation state. The reduction is observed in the complexes with solely neutral Cyp where the ligands number is below 3, higher number protects the Cu(II) state. The metal atom binds to Cyp via 2N of the triazole ring as well as via π–electrons of the benzene ring, additional stabilization brings the interaction with deprotonated OH group. CONCLUSIONS The character of Cyp interactions with doubly charged metals (Cu(II), Zn(II)) clarified the creation of Cyp metabolites. The phenyl and triazole rings are bounded to metal cation and take accessible the isopropyl ring to be cleaved leaving the common metabolite (CAS Number: 58905-19-4).

Electrospray ionization mass spectrometry (ESI-MS) is used to probe the complex formation between tebuconazole (1) and copper(II) salts, which both are commonly used fungicides in agriculture. Experiments with model solutions containing 1 and CuCl2 reveal the initial formation of the copper(II) species [(1)CuCl]+ and [(1)2CuCl]+ which undergo reduction to the corresponding copper(I) ions [(1)Cu]+ and [(1)2Cu]+ under more drastic ionization conditions in the ESI source. In additional experiments, copper/tebuconazole complexes were also detected in samples made from soil solutions of various origin and different amount of mineralization. The direct sampling of such solutions via ESI-MS is thus potentially useful for understanding of the interactions between copper(II) salts and tebuconazole in environmental samples. Copyright © 2011 John Wiley & Sons, Ltd.