Determination of Dinotefuran and Thiamethoxam Residues in Pepper Fruits under Greenhouse Conditions using the QuEChERS Method and HPLC/DAD

DETERMENATION of dinotefuran and thiamethoxam residues levels in pepper samples which were collected randomly at 0, 1, 3, 5, 7, 10, 15 and 21 days after treatment using quick, easy, cheap, effective, rugged, safe (QuEChERS) method and clean up step utilizing solid-phase extraction (SPE) followed by determination by high-performance liquid chromatography with diode-array detection (HPLC/DAD). Dinotefuran and thiamethoxam were recovered within 77-80% and 78-112%, respectively at the spike levels (0.01 - 1 mg/kg) in pepper samples with relative standard deviations (RSDs) lower than 3%. Good linearity was achieved for dinotefuran and thiamethoxam with an excellent correlation coefficient of R-2 >= 0.996 and the matrix matched calibration also showed good linearity with determination coefficients R-2 >= 0.98. The initial deposits of dinotefuran and thiamethoxam in pepper fruits were 6.59 and 1.38 mg/kg, respectively. The half-life period (RL50) of tested pesticides on pepper fruits were 2 and 3.11 days for dinotefuran and thiamethoxam, respectively. According to maximum residue level (MRL) (0.01 mg/kg for dinotefuran and 0.7 mg/kg for thiamethoxam) the pre-harvest interval (PHI) was 11 and 4 days, respectively.