Development of a determination method for six silymarin in powdered milk thistle extract

Abstract

Abstract This study aims to develop a user-friendly and efficient high-performance liquid chromatography method for the detection of six silymarin in powdered milk thistle extract. On the basis of existing standard methods, a simpler prepared mobile phase was used, and the gradient program of mobile phase was optimized. The effectiveness of this method was verified through methodological investigations such as instrument precision experiments, stability experiments, repeatability experiments, and spiked recovery experiments. The method was applied to the detection of 42 batches of actual samples of powdered milk thistle extract. Under optimized mobile phase and gradient elution conditions, six silymarin compounds in powdered milk thistle extract could be effectively separated from the matrix with baseline resolution. There was a good linear relationship between the concentration of the six silymarin compounds in the range of 5~150 μg/mL, with a limit of detection (LOD) of 25 mg/kg. The precision, stability, and repeatability of the method were all below 5%, and the recovery rates at three spiked levels range from 92% to 108%, with RSDs below 4%, indicating its excellent precision and stability. This method was user-friendly and efficient, with good accuracy, making it suitable for the analysis and detection of real samples. During the actual sample testing, significant variations were observed in the content of the six silymarin compounds among different products. The establishment of this method can be utilized for quality control of powdered milk thistle extract products.