Persistence of Combination Fungicide, Fluopyram + Tebuconazole Residues and its Risk Assessment in Kidney Bean

Background: Kidney bean is a protein rich legume crop largely cultivated in hilly tracts of India. Fungal diseases are major biotic constraints causing severe yield losses and fluopyram and tebuconazole are most commonly used for the management of powdery mildew and anthracnose diseases. Hence, studies were taken on dissipation pattern and dietary risk assessment of fungicides to establish consumer safety.
Methods: A simple QuEChERS analytical method was developed and validated for the analysis of fluopyram its metabolite and tebuconazole in kidney bean immature green pods, mature pods, seeds and soil and analyzed in liquid chromatograph mass spectrometer (LC-MS). The combination fungicide was applied as foliar spray at 125+125 and 250+250 g a.i. ha-1 on kidney bean thrice at 10 days interval. Residues were determined in immature green pods, dry mature pods and soil. Immature green pods were collected on 0 (within 2 hours after last spray), 1, 3, 5, 7, 10, 15 and 20 days after third spray and in dry mature pods and soil collected at the time of harvest.
Result: The average recovery and RSD were in the range of 81.63 - 95.48% and 0.55-5.10%, with 0.01 and 0.05 µg mL-1 as LOD and LOQ. The initial concentrations were 0.55 and 1.04 mg kg-1 for fluopyram and 0.57 and 1.03 mg kg-1 for tebuconazole in standard and double dose, respectively. The half-lives were 3.67-4.07 days for fluopyram and 3.86-4.18 days for tebuconazole in standard and double dose. Dietary intake risk of fluopyram and tebuconazole from kidney bean is negligible for adult men, women and children based on RQ values ( less than 1).
