Determination of Residue of Ethephon in Fruits and Vegetables by Ultra- High Performance Liquid Chromatography Tandem Mass Spectrometry with Passing Solid Phase Extraction Purification

A method for the determination of residue of ethephon in fruits and vegetables by passing solid phase extraction purification combined with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was proposed. The sample (5.00 g) was homogenized with 20 mL of water at a high speed for 2 min, and centrifuged for 3 min. The supernatant was made its volume up to 25 mL with water. 5 mL of the above solution was taken through the GCB-HLB composite solid phase extraction column (activated with 5 mL of methanol and 5 mL of water), the first 3 mL of effluent was discarded, and the last 2 mL was collected and passed through 0.22 μm PTFE filter membrane. Ethephon in the filtrate was separated on Dikma Polyamino HILIC column. Multiple reaction monitoring mode was adopted in MS analysis, and external standard method with the working curve made by matrix matched method was used for quantitative analysis. As shown by the results, linear relationships between mass concentration of ethephon in different matrices and the corresponding peak area were found in the range of 2.5-1 000 μg·L^-1, with detection limit (3S/N) of 2.0 μg·kg^-1. Test for recovery was made by the standard addition method, giving results in the range of 81.6%-95.3%, with RSDs (n=6) of the determined values in the range of 4.5%-9.2%. This method was applied to analysis of 56 fruit and vegetable samples, and it was shown that the detection rate of ethephon was 53.4%, and the detection amounts were in the range of 0.023-1.223 mg·kg^-1.