To evaluate the fate variation of chlorantraniliprole with climatic changes of the air temperature and the relative humidity in tomato fruits, the decline rate of chlorantraniliprole residues was investigated in winter and summer seasons, for three consecutive years under field condition. Residues of chlorantraniliprole were determined by high performance liquid chromatography with photodiode array detector (HPLC-DAD). Chlorantraniliprole was sprayed on tomato at recommended dosage. Samples of tomato were collected at one hour, 1, 3, 5, 7, 10 and 15 days after treatment. The decline rates of chlorantraniliprole were described using first-order kinetics. The results indicated that, the half–lives of chlorantraniliprole in tomatoes and the pre-harvest interval (PHI) changed significantly in some cases among winter and summer seasons, and in other cases in the same season in different years of the trial. The least half–life and PHI were 2.441 and 6 d in summer season of 2014, respectively, while the longest were 2.988 and 7.400 d in winter season of 2012, respectively. Also, a negative correlation coefficient was observed with the air temperature and both half–life times and PHIs, while it was a positive in the case of the relative humidity. It was concluded that PHIs may be significantly varied from season to season or from year to year. This work would be helpful to safe use of this insecticide. |
