Determination of synephrine in feeds by a novel quick, easy, cheap, effective, rugged, and safe solid-phase extraction method combined with UHPLC-MS/MS

To detect and quantify synephrine in feed, an effective analytical method based on quick, easy, cheap, effective, rugged, and safe solid-phase extraction coupled to ultra high performance liquid chromatography with tandem mass spectrometry was developed with isotopic internal standards. Pretreatment was performed using quick, easy, cheap, effective, rugged, and safe solid-phase extraction with primary secondary amine and C18 sorbent as sorbents in combination with Oasis MCX column clean-up to extract and purify feed samples. Tandem mass spectrometry detection in positive ion mode was conducted in positive multiple reaction monitoring mode in addition to the quantitative internal standard method. Two transitions of synephrine at m/z 168.1/150.0 and 168.1/135.0 were selected, and m/z 168.1/135.0 was determined as the quantification ion pair. D₉ -Terbutaline was selected as an internal standard, for which m/z 235.1/153.0 was selected as the quantification ion pair. Good linearity was shown for synephrine in the range of 0.5-50 μg/L, and the correlation coefficient exceeded 0.999. The recoveries in three different feed samples at three spiked levels were 81.42-112.08%, and the relative standard deviations were not greater than 14.66%. The method proposed in this study was reliable and highly effective, and its sensitivity, accuracy, and precision are suitable for determining synephrine residues in feed samples.