Mass spectrometry

Mass spectrometry is a useful tool for identifying and characterizing wood samples. Direct analysis in real time mass spectrometry (DART-MS) is a technique used to identify the species and sometimes even the region a piece of wood came from. Wood metabolome profiling could potentially be used for timber species identification, wood fluorescence analysis, and evaluation of the biological degradation of waterlogged or archaeological wood samples. DART-FTICR-MS was used to obtain the mass spectral fingerprints of different timber species. The chemical composition of wood core samples varied between wood, and analysis in real-time mass spectrometry (DART-TOFMS) was used to find the chemistry in wood. Mass spectrometry has also been used for timber origin verification.

Key points about mass spectrometry and wood samples:

  • DART-FTICR-MS was used to obtain the mass spectral fingerprints of different timber species. 
  • DART-MS is a technique used to identify the species and sometimes even the region a piece of wood came from.
  • DART-TOFMS provides a rapid method for wood identification and can accurately and reliably provide species and geographic source wood identification, which would be beneficial in identifying illegally logged and traded timber species

 

Limitations of using mass spectrometry for wood analysis:

  • The complexity of wood samples can make it difficult to analyze. 
  • The laborious sample preparation or derivatization procedures and lengthy chromatographic separations prior to mass analysis in traditional methods for metabolite profiling greatly constrain the development of metabolomics analyses of complex mixtures
  • The accuracy of mass spectrometry for wood analysis can be affected by the quality of the sample
  • The reliability of the chemotypes can vary depending on the database used, and the accuracy of the results can be affected by the quality of the database

 

General steps involved in mass spectrometry analysis of wood samples:

  1. Collection of wood samples: The wood samples must be collected and properly labeled to ensure accurate identification.
  2. Sample preparation: The wood sample must be prepared for analysis. This may involve grinding the sample into a fine powder or extracting specific compounds from the wood. The sample preparation procedure can include solvent choice, sequential extractions, and drying treatments.
  3. Direct analysis: Some techniques, such as direct analysis in real time mass spectrometry (DART-MS), involve analyzing the wood sample directly without any treatment.
  4. Ionization: The sample is ionized, which means that it is given a positive or negative charge. This is typically done using an ion source, which can vary depending on the specific technique used.
  5. Separation: The ionized sample is then separated based on its mass-to-charge ratio. This is typically done using a mass analyzer, which can vary depending on the specific technique used.
  6. Detection: The separated ions are then detected and recorded. This is typically done using a detector, which can vary depending on the specific technique used.
  7. Data analysis: The recorded data is then analyzed to identify the specific compounds present in the wood sample. This may involve comparing the data to a database of known compounds or using statistical analysis to identify patterns in the data.

 

Sample preparation:

  1. grinding the sample into a fine powder
  2. sample is dissolved in an appropriate solvent, such as any organic solvent (e.g., DCM, CHCl3, EtOAc, MeCN, MeOH) or H2O to a concentration of 1mg/mL.
  3. samples are filtered before running the sample to prevent line blockages

 

Examples of solvents:

  • Organic solvents: Organic solvents such as methanol, ethanol, and acetone are commonly used for wood sample preparation in mass spectrometry
  • Water: Water can also be used for wood sample preparation in mass spectrometry, particularly for extracting water-soluble compounds from the wood
  • Acetonitrile: Acetonitrile is another solvent that can be used for wood sample preparation in mass spectrometry
  • Other solvents: Other solvents that have been used for wood sample preparation in mass spectrometry include hexane, dichloromethane, and ethyl acetate

 

Comparation of methods:

  • Traditional wood morphology techniques: Traditional wood morphology techniques involve examining the physical characteristics of the wood, such as the color, texture, and grain pattern. While these techniques can be useful for identifying some species of wood, they may not be sufficient for identifying all species. 
  • Computer vision: Computer vision is a newer technique that involves analyzing digital images of the wood to identify its species.
  • Near infrared spectroscopy: Near infrared spectroscopy is a technique that involves analyzing the absorption of near-infrared light by the wood to identify its species.
  • Gas chromatography-mass spectrometry (GC-MS): GC-MS is a technique that involves separating the compounds in the wood sample using gas chromatography and then analyzing them using mass spectrometry. 


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