From rat brains to tea leaves to the traditional Chinese medicine Atractylodes: domestically produced mass spectrometry imaging instruments continue to yield results in multidisciplinary research

In recent years, the application of mass spectrometry imaging technology has continued to expand in fields such as life sciences, plant metabolism, traditional Chinese medicine research, environmental toxicology and forensic science. The MSI DPI electrospray/photochemical ionisation mass spectrometry imaging source and the MSI LDPI laser/photochemical ionisation mass spectrometry imaging source, developed by Hefei Xinceyuan Instrument Technology Co., Ltd., have yielded high-calibre academic results in numerous applied research projects, thanks to the full polarity detection capabilities and significant increase in sensitivity afforded by post-ionisation technology. These results validate, from various perspectives, the detection capabilities and practical value of domestically produced mass spectrometry imaging ion sources in the analysis of complex samples.

Neuroscience: Non-polar molecules in mouse brain tissue spatially localised for the first time

In neuroscience research, the simultaneous spatial imaging of neurotransmitters and lipids is of great significance for understanding brain function. Traditional DESI mass spectrometry imaging ion sources can only detect polar molecules such as choline, phosphocholine and certain PC lipids, whilst key substances such as GABA, glutamate and cholesterol remain entirely undetectable.

When used for imaging mouse brain sections, the mass spectrometry imaging system equipped with the MSI DPI mass spectrometry imaging source, operating in DESI/PI mode, has successfully detected neurotransmitters and metabolites such as GABA, creatine, glutamine, glutamate and adenosine, as well as cholesterol and more than a dozen neutral GalCer lipids. Notably, the cholesterol signal is 205 times stronger than that obtained with conventional DESI—rising from being virtually undetectable to clearly discernible. The spatial distribution of these non-polar molecules provides previously unobtainable insights for research in neuroscience, pharmacology and neurochemistry.

In negative ion mode, the DESI/PI mass spectrometry imaging source enhances the signal from lipids such as PE-O/PE by a factor of 2–4, whilst the detection sensitivity of metabolites such as glutamate is also improved. The imaging results from the two modes are complementary, providing a more comprehensive spatial molecular distribution map.

The relevant findings were published in *Analytical Chemistry* (2019, 91, 110) and *Rapid Communications in Mass Spectrometry* (2026).

Pathology: Molecular markers of melanocytic naevi show high correlation with H&E staining

In pathological diagnostic research, the MSI DPI mass spectrometry imaging source was used to perform dual-mode (positive and negative ion) imaging on tissue sections of melanocytic naevi.

In positive-ion mode, the DESI and DESI/PI mass spectra exhibited a complementary relationship. The nevus regions were characterised by choline, phosphocholine, S1P, cholesterol, phosphatidylcholine (PC) and sphingomyelin (SM), whilst the normal tissue regions were dominated by non-polar lipids such as MAG, DAG and TG. The specific distribution of S1P, cholesterol, PC34:1 and PC38:4 in the imaging data showed a high degree of concordance with their distribution in the nevus regions as observed in the H&E staining images.

In negative ion mode, the spatial distribution of molecules such as arachidonic acid, FA-C22:6, FA-C24:0, PE O-36:5 and cholesterol sulphate also provided valuable diagnostic information. The imaging results from multiple samples exhibited commonalities, indicating that these molecular markers possess the potential for differentiation and diagnosis.

Immunohistochemical staining further validated the mechanism of cholesterol accumulation in the nevus region—the spatial distribution of the cholesterol imaging maps was consistent with that of the H&E staining images and the TSPO enzyme IHC images.

These findings were published in *Talanta* (2021, 231, 122380), providing a representative case study for the application of mass spectrometry imaging in clinical pathology research.

Plant Metabolism: The complete synthetic pathway of tea leaves visualised spatially for the first time

The study of the spatial distribution of plant metabolites is an important application area for mass spectrometry imaging. The MSI DPI mass spectrometry imaging source demonstrated outstanding detection coverage in imprint imaging of various plant samples.

In tea leaf imprint imaging, the DESI/PI mode detected additional amino acid, catechin and flavonoid metabolites compared to the DESI mode. The signal for theanine increased 14.5-fold, whilst that for caffeine increased 61-fold. More importantly, the DESI/PI mode detected the majority of metabolites along the complete synthetic pathway from chalcones to catechins—information that cannot be obtained using conventional DESI mass spectrometry imaging ion sources. Box-and-whisker plot analysis and t-tests confirmed significant differences in the distribution of theanine between the leaf veins and the leaf blade; spatial correlation analysis of flavonoid metabolites revealed patterns of synergistic distribution among metabolites.

In sage imprint imaging, the DESI/PI mode enabled the detection of monoterpenes, diterpenes and triterpenes. In ginkgo imprint imaging, the DESI/PI mode enabled the detection of flavonoids, ginkgolic acid and cashewol, and revealed the spatial distribution of these metabolites within the secretory cavities. In negative ion mode, the ionic intensity signals of metabolites from both plants increased by approximately one order of magnitude.

The relevant findings were published in *Analytical Chemistry* (2022, 94, 43).

Traditional Chinese Medicine Research: Spatial Evidence Obtained for the Cause of Cinnabar Spots on Atractylodes macrocephala

Red “cinnabar spots” occasionally appear on the surface of the traditional Chinese medicine Atractylodes macrocephala, and their cause has long remained unclear. Hefei Xinceyuan, in collaboration with the China Academy of Chinese Medical Sciences, utilised a DESI/PI mass spectrometry imaging source to perform spatial molecular imaging analysis on Atractylodes macrocephala sections.

The imaging results showed that signals at m/z 183.0807 and m/z 301.2164 were highly correlated with the cinnabar spot regions. Combined with DESI/PI-MSI results for other polyacetylene and sesquiterpene compounds, the study confirmed that the substantial accumulation of Atractylodes macrocephala and specific polyacetylene compounds is the cause of the cinnabar-coloured spots—the colour difference is not due to external staining or contamination, but rather to the spatial localised enrichment of the herb’s own chemical constituents.

These findings, published in *Molecular Horticulture* (2025, 5:11), demonstrate the potential of mass spectrometry imaging in the quality assessment and authenticity verification of traditional Chinese medicinal materials.

Environmental toxicology: Spatial preferential distribution of pollutants in plants

In environmental toxicology research, the MSI DPI mass spectrometry imaging source was utilised to investigate the spatial toxic effects of carbamazepine (CBZ) in tomato plants.

DESI/PI-MSI results indicated that CBZ and its metabolites were primarily concentrated in the marginal regions of tomato leaves, with concentrations at the leaf margins being 2.3 times higher than in the central regions. Liquid chromatography–mass spectrometry (LC-MS) validated this spatial distribution difference. Transcriptomic and metabolomic analyses further revealed significant differences in gene expression and metabolite levels between the inner and outer leaf regions, emphasising the crucial role of spatial location in the CBZ response.

This finding suggests that plant responses to pollutants are not uniformly distributed but exhibit significant spatial preferentiality—mass spectrometry imaging provides an indispensable tool for revealing such spatial heterogeneity.

The relevant findings were published in *Environmental Science & Technology* (2024, 58) and *Analytical Chemistry* (2024, 52).

Forensic Science: Chemical Composition of Fingerprints and Chronological Analysis of Red and Black Pigments

In the field of forensic science, the MSI DPI mass spectrometry imaging source demonstrates unique application value.

In fingerprint imaging, the DESI/PI mode not only clearly reveals the morphological characteristics of fingerprint ridges but also detects chemical constituents such as m/z 369 (cholesterol), m/z 411 (squalene) and m/z 523/537/549 (triglyceride fragments). Fingerprints are no longer merely “shape evidence”; they have also become “chemical evidence”.

In the chronological analysis of red ink and black ink, the mass spectrometry imager accurately distinguished between the two scenarios: “writing first, then stamping” and “stamping first, then writing” : in the ‘stamp first’ group, there was a distinct signal break in the marker ink at the intersection of the red ink and the stamp; in the ‘writing first’ group, the signal from the stamp impression at the intersection was significantly lower than that of the ‘stamp first’ group. The signal characteristics at the intersection were clear, allowing for an uncontested determination.

These applications demonstrate the practical capabilities of mass spectrometry imaging ion sources in forensic evidence analysis.

Application areas continue to expand

In addition to the above fields, the MSI DPI and MSI LDPI mass spectrometry imaging sources have also undergone application validation in the following scenarios:

• Tobacco leaf analysis: Imaging of fresh tobacco leaf sections reveals the spatially specific distribution of plant alkaloids, amino acids and sugars at the leaf tips and margins

• Fossil and lacquerware analysis: MSI LDPI analysed the microspatial distribution of pigments and binders in fossils and lacquerware at a resolution of 2–3 μm

• Mouse retinal imaging: MSI LDPI captured the spatial distribution of metabolites in retinal tissue at the single-cell level

Hefei Xinceyuan stated that the company will continue to expand the application boundaries of mass spectrometry imaging, collaborate with research teams across various fields, and promote the implementation of mass spectrometry imaging technology in more practical scenarios.

About the Product

MSI DPI Electrospray/Photochemical Ionisation Mass Spectrometry Imaging Source: Spatial resolution 20–200 μm, compatible with Agilent/AB SCIEX/Thermo mass spectrometers

MSI LDPI Laser/Photochemical Ionisation Mass Spectrometry Imaging Source: Spatial resolution 2–3 μm, compatible with Agilent/AB SCIEX/Thermo mass spectrometers