Analysis of ethylene glycol in animal feed using liquid chromatography electrospray ionization tandem mass spectrometry

A determination method of ethylene glycol in animal feed by liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was developed. The analysis was performed with a C18 column (150 mm × 4.6 mm, 3.5 µm), and a gradient mobile phase of 0.1 % formic acid solution and acetonitrile. Ethylene glycol and surrogate standard (propylene glycol) were extracted by water at room temperature, derivatized with benzoyl chloride in alkaline medium, and analyzed by LC-ESI-MS/MS. The method has high specificity and selectivity with a detection limit of 0.1 mg/kg, linearity range of 1 - 20 µg/mL, repeatability of 3.08 - 4.41 %, and recovery of  91.1 - 102.0 %, which meet AOAC requirements. This method has been applied to analyze some marketed animal feed samples.