High Performance Liquid Chromatography – Ultraviolet Method for the Determination of Fludioxonil Fungicide Residues: Application on Rice Grains Cultivated in Pakistan

Abstract An analytical method was developed and validated for the determination of fludioxonil in rice samples. Rice samples for the study were collected from different regions of Pakistan. The method was based on safe and cost-effective extraction of fludioxonil from rice grains using acetone and methanol (1:1), efficient clean-up through homogenous mixture of acidic aluminum (12 g) and activated charcoal (1 g) followed by liquid chromatographic determination with UV detection. Quantification was performed on Prospher Star C18 (5 µm, 25 x 0.46 cm) column maintaining the temperature 40ºC and detector wavelength 212 nm using mobile phase 50:50 v/v methanol-water (pH 3.3) employing flow rate 1.0 mL.min-1 and 20 µL injection volume. The method showed linearity with correlation coefficient greater than 0.998. The proposed method was precisely validated for rice sample of all regions, showing recoveries higher than 98%. Rice samples collected from Badin, Multan, Hyderabad, Lahore, Jahania and Sarghoda was found to have fludioxonil residues 0.046, 0.045, 0,043, 0.040, 0.024 and 0.016 mg.kg-1 respectively, all below the maximum residual limit (MRL) level i.e. 0.05 mg.kg-1 whereas samples collected from Khanewal and Gularchi showed fludioxonil residue above MRL i.e 0.065 and 0.058 mg.kg-1 respectively. However, fludioxonil residues was not detected in rice sample collected from city Makhdumpur.