Simultaneous Determination of Isopyrazam and Azoxystrobin in Cucumbers by Liquid Chromatography-Tandem Mass Spectrometry.

A rapid and sensitive analytical method based on high-performance liquid chromatography-tandem mass spectrometry was developed and validated for the determination of isopyrazam (IZM) and azoxystrobin (AZT) in cucumbers. A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was used as the pretreatment procedure. The samples were extracted with acetonitrile and cleaned up with octadecylsilyl silica (C18) and graphite carbon black. The proposed method resulted in satisfactory recovery of IZM and AZT (91.48 to 114.62%), and relative standard deviations were less than 13.1% at fortification concentrations of 1, 20, and 500 μg kg-1 (n = 3). The limits of quantification for IZM and AZT were 0.498 and 0.499 μg kg-1, respectively, which are far below the maximum residue level (0.5 mg kg-1) established for this type of sample. Matrix effects were also evaluated. This study established a sensitive and fast method for the detection of IZM and AZT in cucumber samples.