Chromatographic analysis and residue degradation of phenamacril and difenoconazole on strawberries

Strawberries are widely cultivated and highly consumed globally, but pests and diseases can severely affect yields. Phenamacril and difenoconazole are high-efficacy pesticides and the mixture of these two pesticides offers a satisfactory option for disease control. In this study, an optimised QuEChERS method combined with dispersive solid-phase extraction purification before injection for simultaneously determining the residues of phenamacril–difenoconazole mixture on strawberries was developed and validated using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS). Average recoveries of phenamacril and difenoconazole in the strawberry matrices ranged from 100% to 104% and 99% to 104%, with relative standard deviations of 2.6%–5.3% and 2.2%–5.5%, respectively. The degradation half-lives of phenamacril and difenoconazole were 3.5–6.6 days and 2.2–3.4 days on strawberries, respectively. Final residues of phenamacril and difenoconazole on strawberries at eight different cultivation regions were 0.033–0.66 mg kg⁻¹ and <0.02–0.089 mg kg⁻¹ after spraying at the maximum dosage recommended by the company of 300 mg a.i. kg⁻¹ twice, respectively. Overall, this study is the first report of phenamacril and difenoconazole residue analysis in strawberries. Therefore, it could provide the reference data for safe management and proper use of phenamacril and difenoconazole in China.