The simultaneous degradation of prochloraz and tebuconazole in water with identification and degradation of their main degradation products using liquid chromatography-tandem mass spectrometry.

<title>Abstract</title> Prochloraz and tebuconazole are well-known fungicides for broad-spectrum applications, including; medical, industrial, and agricultural. <bold>They</bold> are frequently used simultaneously for the protection of various agricultural products. The presence of these fungicides in water doesn't only affect the health of direct consumers but also limits their reuse. In this study, complete degradation of these fungicides and their degradation products were accomplished using thermal-activated persulfate. It takes only 30 min to degrade 97% and 98% of PCZ and TBZ, respectively, in their single presence in water using 1.4 mM persulfate and a temperature of 50 ºC. However, it takes one hour to degrade a mixture of PCZ and TBZ at percentages of 99% and 94%, respectively, at the same degradation conditions. The persulfate degradation of prochloraz was conducted by the cleavage of the imidazole ring and the subsequent formation of a trichlorophenol. While, persulfate degradation of tebuconazole was mainly accomplished by the formation of a hydroxyl structure, cleavage of the tert-butyl chain, and the subsequent formation of a di-ketone degradation product. The identification of PCZ and TBZ degradation products was determined using the liquid chromatography-tandem mass spectrometry technique (LC-MS/MS) at both positive and negative modes. The suggested structures of these degradation products and their dissipation were confirmed and monitored, using developed LC-MS/MS multiple reaction monitoring methods.