A modified QuEChERS method for simultaneous determination of flonicamid and its metabolites in paprika using tandem mass spectrometry

• Flonicamid and its metabolites were extracted from paprika using modified QuEChERS.
• Analysis was carried out using tandem mass spectrometry.
• Acidified acetonitrile was used for extraction and sodium chloride as a salting out agent.
• The validated method allows for accurate and precise quantitation of all analytes.
• An undulating residue pattern was observed for all analytes over time.

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) acetate-buffered sample preparation method was developed to improve extraction recovery of flonicamid and its two metabolites (4-trifluoromethylnicotinic acid and N-(4-trifluoromethylnicotinoyl)glycine) in paprika followed by analysis using tandem mass spectrometry. Acidified acetonitrile (containing 5% acetic acid) was used as an extraction solvent and partitioning was carried out using sodium chloride. The extract was then cleaned up using C18. The linearity over a concentration range of 0.005–1 μg/mL was good with a determination coefficient (R2) > 0.9997. Recovery at three different fortification levels was 82.2–101.7% with a relative standard deviation <10 for all analytes. The limit of quantitation of 0.01 mg/kg was quite lower than the maximum residue level set by the Korea Food and Drug Administration (2 mg/kg). The method was successfully applied to determine flonicamid and its metabolites from field incurred samples. The undulating residue pattern observed for the parent analyte together with its metabolites could explain the movement behavior of systemic pesticides into plants over time.