Abstract:A method for the determination of matrine and oxymatrine in goji berries was established by using ultra high performance liquid chromatography-tandem mass spectrometry and isotope internal standard method for quantification. The sample was extracted by ultrasound with a 1.0% phosphoric acid aqueous solution，purified by a strong cation solid-phase extraction column，and eluted with a 5% ammonia methanol solution of 10 mL.The sample was then eluted with a 0.1% formic acid aqueous solution and methanol as the mobile phase. Gradient elution was performed，separated by a T3 chromatographic column，and detected by electron spray ionizqtion positive ion mode multiple reaction mode（MRM）. The optimal pre-treatment method was determined by examining the response values of target compounds under different types of extraction solvents，ultrasound time，and solid-phase extraction conditions. The results showed that there was a good linear relationship between matrine and oxymatrine in the range of 0.5-50.0 μg/kg，with correlation coefficients（R2）greater than 0.999. The detection limit of the method was 0.05 μg/kg，and the quantitative limit was 0.2 μg/kg. The recovery experiment of adding standard at three concentrations of low，medium，and high showed that the recovery rate of matrine ranged from 76.3% to 90.7%，and the relative standard deviation（RSD）ranged from 2.2% to 7.4%；the recovery rate of oxymatrine ranged from 79.2% to 89.0%，and the RSD ranged from 3.1% to 6.6%.This method is fast，simple，accurate，and reproducible，and is suitable for the determination of matrine and oxymatrine in goji berries.