A strategy for fast screening and identification of sulfur derivatives in medicinal Pueraria species based on the fine isotopic pattern filtering method using ultra-high-resolution mass spectrometry

•We provide a new strategy for specifically screening of sulfurous compounds.•The fine isotopic pattern filter (FIPF) bases on separation of 13C2+18O and 34S.•Ultra high resolution mass (100,000 FWHM @ 400 m/z) is essential for FIPF.•IPF is applied to study the unique components of TCM for the first time.•New sulfurous components have been found from Pueraria species.

Sulfurous compounds are commonly present in plants, fungi, and animals. Most of them were reported to possess various bioactivities. Isotopic pattern filter (IPF) is a powerful tool for screening compounds with distinct isotope pattern. Over the past decades, the IPF was used mainly to study Cl- and Br-containing compounds. To our knowledge, the algorithm was scarcely used to screen S-containing compounds, especially when combined with chromatography analyses, because the 34S isotopic ion is drastically affected by 13C2 and 18O. Thus, we present a new method for a fine isotopic pattern filter (FIPF) based on the separated M + 2 ions (12Cx1Hy16Oz32S13C218O, 12Cx+21Hy16Oz+134S, tentatively named M + 2OC and M + 2S) with an ultra-high-resolution mass (100,000 FWHM @ 400 m/z) to screen sulfur derivatives in traditional Chinese medicines (TCM).This finer algorithm operates through convenient filters, including an accurate mass shift of M + 2OC and M + 2S from M and their relative intensity compared to M. The method was validated at various mass resolutions, mass accuracies, and screening thresholds of flexible elemental compositions. Using the established FIPF method, twelve S-derivatives were found in the popular medicinal used Pueraria species, and 9 of them were tentatively identified by high-resolution multiple stage mass spectrometry (HRMSn). The compounds were used to evaluate the sulfurous compounds' situation in commercially purchased Pueraria products. The strategy presented here provides a promising application of the IPF method in a new field.

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