Dissipation Pattern and Effect of Washing on Reduction of Dimethoate Residues on Sweet Orange, Citrus sinensis L.

Dissipation pattern of dimethoate residues on fruits of sweet orange (Musambi) and reduction of residues by washing is reported. Residues were determined by gas liquid chromatography (GC) equipped with flame thermionic detector (FTD). The residues of dimethoate in rind dissipated with time regularly showing 85.00 and 88.24 per cent dissipation by 10^th d after spray at the recommended (468.7 g a.i. ha⁻¹) and double (937.4 g a.i. ha⁻¹) doses respectively. In pulp, the residues reached below detectable level (BDL) of 0.01 mg kg⁻¹ by 7^th d in recommended dose and 10^th d in double dose. No residues were found on 0 d within detectable level of 0.01 mg kg⁻¹ in recommended dose after washing whereas in double dose, 80.39 per cent reduction was observed.