Development and validation of an ultra-performance liquid chromatography-tandem mass spectrometry method for the residue analysis of pyraclostrobin in Malus domestica leaves

A new method was developed for the residue determination of pyraclostrobin in Malus domestica leaves. The recovery rates of pyraclostrobin with three pretreatment methods were investigated and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was employed for the analysis. Results showed that Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) had a better recovery, required less solvent and shorter time. In the purification procedure of QuEChERS, only two substances, PSA and GCB, were added. Good extracting and purification results can be obtained by using PSA and GCB with the dosages of 0.025 and 0.020 mg/mL respectively. Apple leaf tissues had slight enhancement matrix effect in the residue analysis of pyraclostrobin. In this work, a method for the residue analysis of pyraclostrobin in apple leaves was developed by using the improved QuEChERS method and the UPLC-MS/MS instrument. Following the proposed method, the linearity was in the range of 0.01-50.0 mg/L with the quantitation limit (LOQ) of 0.01 mg/kg and the recovery ranged between 92% and 99% with the RSD range of 2.2%-5.3%. The proposed method was applied to study the residue dynamic of pyraclostrobin in apple leaves. The detected data of pyraclostrobin residue in apple leaves can be well described by the first order kinetics equation ct=79.87 e-0.053 3 t, and the half-life period (DT50) was 13 days according to this model.