Determination of Abamectin Residue in Paprika by High-Performance Liquid Chromatography

Reversed-phase high-performance liquid chromatography (HPLC) techniques were developed to quantify abamectin (ABM) in paprika (Capsicum annum). Separation was achieved on a C₁₈ ODS column with a mobile phase of acetonitrile/water (96/4, v/v) mixture in an isocratic elution at the flow tate of 1.2 mL/min for avermectins (AVMs). The retention times were 8.0 and 9.7mins for AVM Blb and AVM B₁ₐ , respectively. Residual AVMs (sum of AVM B₁ₐ , AVM B1b and 8,9-Z-AVM B₁ₐ ) in the vegetable were extracted with acetonitrile, and the silica solid-phase extraction cartridges were used to purify the extract. AVMs were derivatized using trifluoroacetic acid and 1-methylimidazole, and the derivatives were determined with a fluorescence detector (excitation at 365 nm and emission at 470 nm). High and consistent recoveries, ranging from 93% to 115%, were obtained for AVM B₁ₐ and 8, 9-Z-AVM B₁ₐ at fortified levels of 20μg/kg\;and\;200μg/kg for paprika. The limit of quantitation (LOQ) was 2μg/kg . The residual levels of AVMs in paprika in a field experiment from one day to seven days after the last application decreased from 18.40 to 7.59μg/kg . The half-life (T1/2) of AVMs in paprika was 1.47 days.