Determination of Ethoxyquin Residues in Fruits by HPLC-MS/MS

A method for analysis of trace ethoxyquin residues in apple and pear was developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The ethoxyquin residues in alkali sample solution were partitioned into hexane, and C₁₈ reverse phase column was applied as the analytical column. Appropriate formic acid and ammonium acetate were added into mobile phase to optimize the shape of chromatographic peak. One parent ion of m/z 218.1 and two daughter ions of m/z 147.9 and m/z 175.9 were selected as quantitive and qualitative ions. Limit of detection (LOD) is 5 μg•kg^-1, and the linear range is 20200 μg•L^-1. The recoveries in three spkied level are in the range of 86.6%-91.7％， with relative standard deviation(RSD) of 4.8%-5.3％.