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Direct characterization of bulk samples by internal extractive electrospray ionization mass spectrometry.

Zhang H, Gu H, Yan F, Wang N, Wei Y, Xu J, Chen H - Sci Rep (2013)

Bottom Line: The method allows both qualitative and quantitative analysis of analytes distributed in a 3-dimensional volume (e.g., 1 ~ 100 mm(3)) of various synthetic and biological matrices (e.g., chewing gum, leaves, fruits, roots, pork, lung tissues) without either mashing the sample or matrix separation.Using different extraction solvents, online chromatographic separation of chemicals inside the sample volume was observed during iEESI-MS analysis.The presented method is featured by the high speed of analysis, high sensitivity, low sample consumption and minimal sample preparation and/or degradation, offering unique possibilities for advanced applications in plant science, clinical diagnosis, catalyst studies, and materials science.

View Article: PubMed Central - PubMed

Affiliation: Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China Institute of Technology, Nanchang, Jiangxi 330013, China.

ABSTRACT
A straight-forward analytical strategy called internal extractive electrospray ionization mass spectrometry (iEESI-MS), which combines solvent extraction of chemicals inside a bulk sample with in situ electrospray ionization mass spectrometry, has been established to directly characterize the interior of a bulk sample with molecular specificity. The method allows both qualitative and quantitative analysis of analytes distributed in a 3-dimensional volume (e.g., 1 ~ 100 mm(3)) of various synthetic and biological matrices (e.g., chewing gum, leaves, fruits, roots, pork, lung tissues) without either mashing the sample or matrix separation. Using different extraction solvents, online chromatographic separation of chemicals inside the sample volume was observed during iEESI-MS analysis. The presented method is featured by the high speed of analysis, high sensitivity, low sample consumption and minimal sample preparation and/or degradation, offering unique possibilities for advanced applications in plant science, clinical diagnosis, catalyst studies, and materials science.

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Mass spectral patterns recorded from identical chewing gum samples by different ionization techniques.a) iEESI; b) DESI; c) “leaf spray” (direct ESI from the microdroplet spotted on the sample surface).
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f2: Mass spectral patterns recorded from identical chewing gum samples by different ionization techniques.a) iEESI; b) DESI; c) “leaf spray” (direct ESI from the microdroplet spotted on the sample surface).

Mentions: In a model experiment, chemical composition of a chewing gum (Kent®, USA) was characterized by iEESI-MS (Fig. 2a). Rich MS fingerprint was detected by iEESI-MS in a broad mass range (m/z 100–1000) with good signal abundance (3.73E4 cps). The chemical ingredients such as glycerol, menthol, menthone, glucose and sucrose (Supplementary Table S1) were successfully identified by iEESI-MSn experiments. The distribution of equally spaced peaks at m/z 262, 348, 434, and 520 (Supplementary Fig. S1) was tentatively attributed to polyvinyl acetate, an essential component of the chewing gum. Remarkably different from iEESI-MS, DESI mass spectrum was dominated by low-mass signals (m/z < 300), among which the polyvinyl acetate signals were totally absent (Fig. 2b). In another sampling approach – so-called “leaf spray”28 – a drop of methanol (5 μL) was deposited on the gum surface for chemical extraction, and ionic spray was generated by applying high voltage directly to the sample. This approach produced mass spectrum spanning a wide m/z range (Fig. 2c), but the abundance of most signals was, on the average, 2 orders of magnitude lower than those detected by iEESI-MS. Note that the signal density of the “leaf spray” experiment was heavily dependent on the volume of methanol added onto the chewing gum. No signal was detectable if the chewing gum was not sufficiently wet to generate charged plume. Extra experiments were carried out by iEESI-MS to evaluate its feasibility for direct characterization of other bulk samples. Similar to the chewing gum analysis, considerably richer mass spectral patterns for iEESI-MS were also obtained using mammal and plant raw samples including pork meat (Supplementary Fig. S2), garlic leaf (Supplementary Fig. S3), and garlic bulb tissue (Supplementary Fig. S4). Even though default instrument parameters were used in all the three methods considered, care should be taken not to make definitive conclusions based on limited data at this stage.


Direct characterization of bulk samples by internal extractive electrospray ionization mass spectrometry.

Zhang H, Gu H, Yan F, Wang N, Wei Y, Xu J, Chen H - Sci Rep (2013)

Mass spectral patterns recorded from identical chewing gum samples by different ionization techniques.a) iEESI; b) DESI; c) “leaf spray” (direct ESI from the microdroplet spotted on the sample surface).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750536&req=5

f2: Mass spectral patterns recorded from identical chewing gum samples by different ionization techniques.a) iEESI; b) DESI; c) “leaf spray” (direct ESI from the microdroplet spotted on the sample surface).
Mentions: In a model experiment, chemical composition of a chewing gum (Kent®, USA) was characterized by iEESI-MS (Fig. 2a). Rich MS fingerprint was detected by iEESI-MS in a broad mass range (m/z 100–1000) with good signal abundance (3.73E4 cps). The chemical ingredients such as glycerol, menthol, menthone, glucose and sucrose (Supplementary Table S1) were successfully identified by iEESI-MSn experiments. The distribution of equally spaced peaks at m/z 262, 348, 434, and 520 (Supplementary Fig. S1) was tentatively attributed to polyvinyl acetate, an essential component of the chewing gum. Remarkably different from iEESI-MS, DESI mass spectrum was dominated by low-mass signals (m/z < 300), among which the polyvinyl acetate signals were totally absent (Fig. 2b). In another sampling approach – so-called “leaf spray”28 – a drop of methanol (5 μL) was deposited on the gum surface for chemical extraction, and ionic spray was generated by applying high voltage directly to the sample. This approach produced mass spectrum spanning a wide m/z range (Fig. 2c), but the abundance of most signals was, on the average, 2 orders of magnitude lower than those detected by iEESI-MS. Note that the signal density of the “leaf spray” experiment was heavily dependent on the volume of methanol added onto the chewing gum. No signal was detectable if the chewing gum was not sufficiently wet to generate charged plume. Extra experiments were carried out by iEESI-MS to evaluate its feasibility for direct characterization of other bulk samples. Similar to the chewing gum analysis, considerably richer mass spectral patterns for iEESI-MS were also obtained using mammal and plant raw samples including pork meat (Supplementary Fig. S2), garlic leaf (Supplementary Fig. S3), and garlic bulb tissue (Supplementary Fig. S4). Even though default instrument parameters were used in all the three methods considered, care should be taken not to make definitive conclusions based on limited data at this stage.

Bottom Line: The method allows both qualitative and quantitative analysis of analytes distributed in a 3-dimensional volume (e.g., 1 ~ 100 mm(3)) of various synthetic and biological matrices (e.g., chewing gum, leaves, fruits, roots, pork, lung tissues) without either mashing the sample or matrix separation.Using different extraction solvents, online chromatographic separation of chemicals inside the sample volume was observed during iEESI-MS analysis.The presented method is featured by the high speed of analysis, high sensitivity, low sample consumption and minimal sample preparation and/or degradation, offering unique possibilities for advanced applications in plant science, clinical diagnosis, catalyst studies, and materials science.

View Article: PubMed Central - PubMed

Affiliation: Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China Institute of Technology, Nanchang, Jiangxi 330013, China.

ABSTRACT
A straight-forward analytical strategy called internal extractive electrospray ionization mass spectrometry (iEESI-MS), which combines solvent extraction of chemicals inside a bulk sample with in situ electrospray ionization mass spectrometry, has been established to directly characterize the interior of a bulk sample with molecular specificity. The method allows both qualitative and quantitative analysis of analytes distributed in a 3-dimensional volume (e.g., 1 ~ 100 mm(3)) of various synthetic and biological matrices (e.g., chewing gum, leaves, fruits, roots, pork, lung tissues) without either mashing the sample or matrix separation. Using different extraction solvents, online chromatographic separation of chemicals inside the sample volume was observed during iEESI-MS analysis. The presented method is featured by the high speed of analysis, high sensitivity, low sample consumption and minimal sample preparation and/or degradation, offering unique possibilities for advanced applications in plant science, clinical diagnosis, catalyst studies, and materials science.

Show MeSH
Related in: MedlinePlus