Liquid chromatography-tandem mass spectrometry quantification of acetamiprid and thiacloprid residues in butterbur grown under regulated conditions

- Acetamiprid and thiacloprid were quantified in butterbur using LC-MS/MS.
- Both analytes were extracted with acetonitrile and purified with Florisil cartridge.
- LL partitioning in combination with SPE effectively removed the interferences during purification.
- The developed method determined both analytes accurately and precisely.
- The residual levels in field-incurred butterbur samples decreased with time and number of treatments.

An analytical method was developed to quantify the residual levels of the neonicotinoid insecticides, acetamiprid and thiacloprid, in field-incurred butterbur samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Samples were extracted with acetonitrile and partitioned with dichloromethane. After partitioning, purification was conducted using a Florisil® cartridge. Linearity of a matrix-matched calibration curve of the two compounds over a concentration range of 0.004-0.4 μg/g was excellent, with determination coefficients (R2) ≥ 0.9998. The limits of detection (LOD) and quantitation (LOQ) for both acetamiprid and thiacloprid were 0.0006 and 0.002 mg/kg, respectively. The average recoveries for acetamiprid and thiacloprid at two spiking levels (0.02 and 0.1 mg/kg, i.e., 10 × LOQ and 50 × LOQ) were between 78.23 to 82.17%, with relative standard deviations (RSDs) ≤ 7.22%. The method was successfully applied to field-incurred samples treated with a commercial pesticide product, either once (zero or 7 days before harvest) or twice (0 and 7, 7 and 14, or 14 and 21 days before harvest). The highest and lowest residues were obtained for the 7 and 0 days' treatment and the 21 and 14 days' treatment, respectively. The developed method is simple and accurate and can be extrapolated to other leafy vegetables.

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