Abstract: Objective To establish a high-performance liquid chromatography (HPLC) method for simultaneous determination of contents of four aflatoxins in Polygalae Radix medicinal materials. Methods An Ultimate XB-C₁₈ column (4.6 mm×150 mm, 5 μm) was used as the stationary phase with methanol (A)-acetonitrile (B)-water (C) (22∶10∶68) as the mobile phase. The flow rate was 0.7 mL·min^-1 and the column temperature 40°C. A fluorescence detector (λ_ex=360 nm, λ_ex=450 nm) was adopted, and the injection volume was 10 μL. The effects of extraction and purification were compared between different methods of extraction and between immunoaffinity columns of different brands. The pretreatment process was optimized, and the difference that matrix effects made in detection results was investigated. The aflatoxin levels of 28 batches of Polygalae Radix herbs and decoction pieces were tested. Results The results of the methodological investigation met the requirements of quality analysis of traditional Chinese medicine. AFG₂ and AFB₂ showed a good linear relationship within the range of 0.000 075 to 0.075 μg·mL^-1, compared to 0.000 25 to 0.25 μg·mL^-1 for AFG₁ and AFB₁.The correlation coefficients were 0.999 9. The matrix effect ranged from 94.49% to 103.51%, indicating that the Polygalae Radix matrix had no significant impact on the determination of aflatoxins. The average recovery of AFG₂, AFG₁, AFB₂, and AFB₁ at low, medium and high concentrations was 78.98% to 93.51%, 81.88% to 100.74%, and 82.19% to 116.12%, respectively, with RSDs ranging from 1.1% to 6.6%. For Polygalae Radix, a homogenizer was a better means to extract aflatoxins before enriching them with the immunoaffinity columns. Among the 28 batches of Polygalae Radix samples, 2 batches of crude drugs were found to be substandard. The highest total content of aflatoxins was 313.63 μg·kg^-1 and the AFB₁ content was as high as 143.27 μg·kg^-1. Conclusion A simple and reliable new method for simultaneous determination of four aflatoxins in Polygalae Radix medicinal materials has been established, which can overcome the flaws of existing detection methods currently available and expose the risk of aflatoxin contamination in Polygalae Radix.

Key words: Polygalae Radix, Aflatoxins, High Performance Liquid Chromatography-Fluorescence Detector, Matrix Effects