[Determination of the key characteristic components in ginger from different origins by internal extractive electrospray ionization mass spectrometry].

Abstract

Ginger， the fresh rhizome of Zingiber officinale Rosc. from the Zingiberaceae family， is highly valued worldwide for its unique aromatic profile and distinct pungent flavor. It is widely utilized both as a culinary spice and a natural food additive. Globally， ginger comprises 53 known genes and approximately 1 300 varieties， predominantly cultivated in tropical and subtropical regions. Major producing countries include India， China， Indonesia， and Nigeria， with China ranking as the second-largest producer. In many Asian countries， such as China， Korea， and Japan， ginger has long been recognized not only for its culinary applications but also for its medicinal properties. It is traditionally employed to alleviate cold symptoms， promote body warmth， reduce nausea， suppress coughs by clearing phlegm， and even neutralize toxins from seafood consumption. The efficacy and safety of ginger as a medicinal herb are largely determined by the content and purity of its active constituents， such as gingerols and shogaols. Thus， accurate quality assessment is essential to ensure its therapeutic value. Moreover， the contents of these bioactive compounds can vary considerably depending on the geographical origin. In China， high-quality medicinal ginger is primarily cultivated in provinces such as Yunnan， Sichuan， Guizhou and Henan. Given the complexity and diversity of ginger's chemical composition， it is crucial to understand its characteristic components and their variation with origin. This knowledge supports not only accurate quality evaluation but also reliable traceability of ginger sources. Ultimately， it facilitates the selection of ginger with superior medicinal properties for direct use in traditional medicine or as high-quality raw material in pharmaceutical development. However， conventional analytical techniques for determining origin and quality， such as high performance liquid chromatography （HPLC） and gas chromatography-mass spectrometry （GC-MS）， are often time-consuming， require extensive sample preparation， and consume large volumes of solvents. To overcome these limitations， this study developed a high-throughput method based on internal extractive electrospray ionization mass spectrometry （iEESI-MS） for rapid compositional profiling and origin authentication of ginger. Samples were collected from four major ginger-producing regions in China： Yunnan， Sichuan， Guizhou， and Henan. Each sample was minimally processed into fragments， with only 5.0 mg used for analysis. The fragments were placed on a filter membrane inside a custom-built iEESI-MS device. Key instrumental parameters such as the extraction solvent composition， ion transfer tube temperature， spray voltage， and solvent flow rate were systematically optimized to enhance detection sensitivity and reproducibility. Under optimal conditions， real-time extraction and ionization of chemical constituents from ginger tissue were achieved， yielding representative mass spectral fingerprints for each geographical origin. Multivariate statistical tools were applied to interpret the complex mass spectrometry data. Principal component analysis （PCA） provided an overview of sample distribution and revealed inherent clustering trends according to origin. Partial least squares discriminant analysis （PLS-DA） further improved the classification accuracy by filtering out unrelated variations and emphasizing the ions that contributed most to inter-regional differences. Through this approach， 27 compounds were consistently detected and identified， among which three key markers， such as 6-gingerol， 8-gingerol， and L-serine， were selected as characteristic of origin-related variation. A quantitative method was developed for these three markers， demonstrating excellent linearity across a broad content range （2.0-20 000.0 μg/g） with coefficients of determination （R²） exceeding 0.996. Sensitivity was assessed in terms of limits of detection and limits of quantification， which ranged from 3.0 μg/g to 20.0 μg/g and 10.0 μg/g to 50.0 μg/g， respectively. Recoveries varied between 99.7% and 100.9%， indicating high accuracy， while repeatability was excellent， with relative standard deviation （RSD） values below 1.6%. When the established method was applied to ginger samples from different regions， heatmap visualization clearly illustrated the correlation between geographic origin and the abundance of the three characteristic compounds. For instance， Yunnan samples exhibited notably higher contents of certain gingerols， whereas those from Henan were richer in L-serine. This chemical fingerprinting strategy offers a reliable and efficient means for rapid origin verification and quality assessment. In conclusion， the iEESI-MS platform developed in this study combines minimal sample preparation， rapid analysis， and high sensitivity， making it well-suited for high-throughput applications. It holds significant potential not only for ginger authentication but also for quality control of other medicinal plants， food traceability systems， and the protection of geographically indicated products. Future studies may expand the database to include more regions and varieties， further improving the robustness and general applicability of the model.