An analytical method was developed for the quantification of spinosad (sum of spinosyns A and D) in five animal-derived products (chicken breast, pork, beef, egg, and milk) using LC-MS/MS. The sample was extracted using acetonitrile/1% acetic acid and a combination of magnesium sulfate and sodium acetate salts. The sample was purified using multiwalled carbon nanotubes as sorbent via a dispersive-solid-phase extraction procedure. Matrix-matched calibration (seven-point) provided good linearity with coefficient of determination (R2 ) ≥0.99 for each product. The limits of detection and quantification (LOQs) ranged between 0.0003-0.03 and 0.001-0.1 mg/kg, respectively. Method validation was carried out after spiking the target standard to blank matrices at the concentration levels of LOQ, 2 × LOQ, and 10 × LOQ with three replicates for each. The average recoveries were between 74 and 104%, with relative standard deviations ≤9.68, which were within the acceptable range designated by the international organizations. The developed method was successfully applied for monitoring market samples collected throughout the Korean Peninsula, and none of the samples tested positive for the target analytes. It has therefore been shown that dehydration and acidification were effective to extract spinosad from animal-derived products.
Keywords: MS/MS, sample preparation; animal-derived product; spinosyns A and D.
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