A Dilute-and-Shoot Based UPLC-MS/MS Method for Multimycotoxins Analysis in Astragali radix

Background: Astragali radix is prone to be contaminated by various mycotoxins, leading to unpredictable threats on the quality and safety of Astragali radix and the health of the consumers. Therefore, the determination of multimycotoxins is imperative. Objective: To develop an efficient, sensitive, fast, and multianalyte method for detecting multimycotoxins in Astragali radix. Methods: A selective dilute-and-shoot pretreatment procedure based ultra-performance LC-tandem MS (UPLC-MS/MS) method was developed for sensitive determination of multimycotoxins in Astragali radix, including aflatoxin (AF) B₁, B₂, G₁, G₂, and ochratoxin A. The five mycotoxins were extracted by the dilute-and-shoot pretreatment procedure followed by UPLC-MS/MS detection. Types of sample extraction solvent, mobile-phase compositions and MS/MS parameters, and dilute-and-shoot conditions were optimized. Results: The optimized chromatographic and mass spectrometric conditions allowed the separation and detection of the five mycotoxins within 5 min. The validated UPLC-MS/MS method exhibited good sensitivity with LOD and LOQ lower than 0.2 and 0.5 μg/kg, respectively. RSD values for method precision were lower than 9%. Recoveries obtained were between 90.87 and 108.44% for all the analytes with RSDs of 3.96-8.03%. The developed method was applied for the detection of the 5 mycotoxins in 18 batches of Astragali radix with good determination performance and no matrix interferences. Two samples collected from Shanxi province and Neimenggu Autonomous Region in China were positive for AFB₁ at 3.24 and 2.69 μg/kg, respectively. Conclusions: The dilute-and-shoot procedure allowed for the extraction of the mycotoxins with advantages of simple pretreatment, small extraction time, high selectivity and accuracy, as well as being cost effective and easy to operate without any clean-up steps. Highlights: This is the first report on dilute-and-shoot approach for mycotoxins extraction and detection in Chinese medicinal material matrixes.