Effect of processing on reduction of λ-cyhalothrin residues in tomato fruits

Persistence behaviour of λ-cyhalothrin in tomato fruits was studied following application with recommended (15 g a.i. ha(-1)) and double the recommended (30 g a.i. ha(-1)) dosage of λ-cyhalothrin at fruiting stage under two different temperature conditions. Samples were collected on 0 (1 h after spray), 1, 3, 5, 7, 10 and 15 days after application. Effects of processing like washing, washing followed by boiling were studied to dislodge the residues of λ-cyhalothrin on tomato fruits. Residues were estimated by GC-ECD capillary system. Residues of λ-cyhalothrin persisted up to 7 days in tomato fruits. The half-life (t (1/2)) periods were observed to be 2.07 and 1.88 days at room temperature and 2.35 and 2.02 days under refrigerated condition for single and double dose, respectively. The process of washing followed by boiling reduced the residues effectively (74-84%) whereas by washing only, residues could be reduced in the range of 37-40%. In samples under refrigerated condition, residues decreased slightly less than the samples stored under room temperature. Washing followed by boiling reduced the residues from 72 to 80% whereas only washing reduced the residues from 35 to 36% In soil samples, residues of λ-cyhalothrin reached below detectable level of 0.005 mg kg(-1) on 3rd and 7th day at single and double dose, respectively.