Abstract: A method for the determination of six illegally added digitalis drugs (methyldigoxin, digoxin, deslanoside, digitoxin, strophanthidin, lanatoside C) in health foods was established by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were dispersed in water, then extracted with acetonitrile, and finally salted out with sodium chloride. The chromatographic separation was performed on a HSS T3 column with gradient elution using a mobile phase consisting of acetonitrile and 20 mmol/L ammonium acetate solution (containing 0.1% (V/V) aqueous formic acid). The mass spectrometer was operated in both positive and negative ion modes using multiple reaction monitoring (MRM), and quantitative analysis was performed using a matrix-matched external standard method. Under the optimized conditions, good linearity was obtained for all analytes over the concentration range investigated with determination coefficients (R2) greater than 0.995. The average recovery rates at three different spiked levels ranged from 83.9% to 107.0%, with relative standard deviations (RSDs) in the range of 0.7%–7.1% (n = 6), and the limits of quantification were between 0.022 6 and 0.088 5 mg/kg. The method has the advantages of simple and efficient pretreatment, fast analysis speed, high sensitivity, accurate and reliable quantification, and can meet the requirements for high-throughput rapid detection of illegally added digitalis drugs in health foods.

Key words: health foods; illegally added digitalis drugs; ultra-high performance liquid chromatography-tandem mass spectrometry