Study on matrix effects in the detection of 15 pesticide residues in 6 types of tea leaves

  Objective  Matrix effects in detecting 15 pesticide residues in six types of tea using gas chromatography-tandem mass spectrometry (GC-MS/MS) with a sample pretreatment of QuEChERS were analyzed for assay improvement.

  Methods  Tea samples were pretreated with QuEChERS, and solvent and matrix standard curves for the mass concentrations of 0.01-0.32 mg·L⁻¹ prepared. After a GC-MS/MS determination, the matrix effects were calculated.

  Results  Matrix effects were enhanced in the determination that ranged from 1.35-411.58% with the strong, medium, and weak matrix effects of 73.33%, 23.33%, and 3.33%, respectively. When black tea was used as an alternative matrix, they ranged 0.62-59.22% with the strong, medium, and weak matrix effects at 1.33%, 14.67% and 84.00%, respectively. Whereas, when a mixed tea was applied as an alternative matrix, suppressed matrix effects resulted at 0.09-48.09% with the strong, medium, and weak matrix effects at 0, 13.33% and 86.67%.

  Conclusion  The matrix effects in the pesticide residue detection on teas were complex. Application of a matrix standard curve reduced the matrix effects and improved the determination accuracy. By using mixed tea sample as an alternative matrix, the analysis efficiency was significantly enhanced.