In situ generation of copper cations and complexation with tebuconazole in a hyphenation of electrochemistry with mass spectrometry

Tebuconazole (1) belongs to a class of widely utilized plant fungicides, mostly in vineyards. Consequently, traces of this compound are present in plant tissues, wine as well as in soil. The aim of this study was in situ generation of Cu cations and creation of very stable Cu complexes with 1. The proposed method involves a hyphenation of electrochemistry with electrospray ionization mass spectrometry (ESI-MS), based on the high affinity of 1 for dissolved copper cations. We demonstrate that at appropriate potentials (above 500 mV vs. silver reference electrode) Cu cations can be generated in an electrochemical cell, which subsequently form complexes with 1 present in the sample. The resulting complex [Cu(1)]+ as well as its fragment [Cu(1-C4H10)]+ are then detected with online-coupled ESI-MS. This finding is useful for a creation of an analytical method based on the detection of trace amounts of 1 in complex matrices (e.g., soil solution), in which the analyte may be spread among various species.

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► Alternative detection of tebuconazole in environmental matrices is designed.
► Electrospray ionization mass spectrometry is hyphenated with electrochemistry.
► Cu cations generated in electrochemical cell form stable tebuconazole complexes.
► Cu/tebuconazole complexes are detected using the online-coupled ESI-MS.