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Scientists have developed an automatic and highly efficient method to authenticate single herbal powders using microscopy-guided in situ auto-sampling combined with matrix-assisted laser desorption–ionization mass spectrometry (MALDI–MS).
Researchers at China Pharmaceutical University in Nanjing have developed a new method to authenticate single herbal powders using microscopy and mass spectrometry. In a recent study published in Analytical Chemistry, the team led by Bin Li presents a label-free, automatic approach for the identification of single herbal powders and their adulterants (1).
While microscopic examination has long been used to identify the morphology of herbal powders, it cannot provide the chemical profiles necessary for authentication. To address this limitation, the researchers combined microscopy-guided auto-sampling with matrix-assisted laser desorption–ionization mass spectrometry (MALDI–MS).
MALDI–MS is a technique that allows for the analysis of large molecules, such as proteins and peptides. In this technique, the molecule of interest is embedded in a matrix, which absorbs energy from a laser. The absorbed energy leads to the vaporization and ionization of the matrix and the embedded molecule, which are then accelerated in an electric field and separated by their mass-to-charge ratio. The resulting mass spectrum provides information about the molecular weight and structure of the molecule, allowing for identification and quantification. MALDI–MS is widely used in fields such as proteomics, pharmaceuticals, and biomarker discovery.
The researchers applied a gelatin coating to a glass slide to immobilize the dried herbal powders that did not adhere well to the slide. This also facilitated the extraction of chemical components and prevented diffusion. Optical microscopy was then used to identify the microstructure and position of the herbal powders on the gelatin-coated slide. The candidate single herbal powders were then automatically sampled and identified by MALDI–MS.
According to the researchers, the combination of microstructure features and chemical profiles significantly improved the authentication capability of microscopic examination. This is significant because herbal products are widely used for medicinal purposes, and their quality and safety can be compromised by the presence of adulterants. The method can be used to identify single herbal powders and their adulterants, which is important for ensuring the safety and efficacy of herbal products.
In conclusion, the new method developed by the researchers at China Pharmaceutical University in Nanjing can provide an automatic, label-free approach for the identification of single herbal powders and their adulterants. The combination of microscopy and mass spectrometry significantly improves the authentication capability of microscopic examination, which can help ensure the quality and safety of herbal products.
(1) Sun, S.; Tang, W.; Li, B. Authentication of Single Herbal Powders Enabled by Microscopy-Guided In Situ Auto-sampling Combined with Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry. Anal. Chem. 2023. DOI: https://doi.org/10.1021/acs.analchem.2c05517