An analytical technique that measures the mass-to-charge ratio of ions. The purpose is to identify the amount and type of chemicals present in a sample by measuring the mass-to-charge ratio and abundance of gas-phase ions.
MALDI-TOF is a “soft ionization” technique, ideal for analyzing large biomolecules like proteins and peptides without causing fragmentation. By mixing the sample with a matrix and using a laser pulse, it ionizes the sample. Its key differentiator is its ability to rapidly analyze large molecules, making it especially useful in proteomics and microbial identification.
ESI operates by passing a sample solution through a high-voltage needle, creating charged droplets that produce ions. Its versatility stands out, as it can ionize a broad range of compounds, from small molecules to large proteins. ESI’s compatibility with Liquid Chromatography (LC) allows for seamless separation and subsequent MS analysis, making it a go-to for metabolomics and lipidomics.
MS/MS is a two-stage process where ions are first separated, selected ions are fragmented, and then the fragments are analyzed. Its strength lies in providing detailed structural information, especially for peptides. By targeting specific ions and monitoring their fragments, MS/MS offers unparalleled specificity and precision, making it invaluable for proteomics and pinpoint quantitative analysis.
The process of preparing biological samples for analysis by mass spectrometry (MS). This involves extracting, purifying, and concentrating the molecules of interest from a complex mixture. The main purpose is to ensure that the sample is in a suitable form for MS analysis, free from contaminants that might interfere with the MS readings, and concentrated enough to be detected.
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GC-MS specializes in analyzing volatile and thermally stable compounds. Fusing the separation capabilities of gas chromatography with the identification prowess of mass spectrometry, it’s commonly employed in forensics, environmental monitoring, and flavor profiling. Its strength lies in the precise identification of organic compounds using well-established libraries.
LC-MS extends the applicability of mass spectrometry to thermally labile and non-volatile compounds. By integrating the broad separation power of liquid chromatography with detailed mass spectrometric analysis, it becomes invaluable in proteomics, drug development, and metabolite profiling. It stands out for its ability to handle larger and diverse molecules, bridging gaps left by GC-MS.
|Overview||Gas chromatography coupled with mass spectrometry||Liquid chromatography coupled with mass spectrometry|
|Sample Type||Volatile and thermally stable compounds||Non-volatile and thermally labile compounds|
|Ionization Techniques||Electron Impact (EI), Chemical Ionization (CI)||Electrospray Ionization (ESI), Atmospheric Pressure Chemical Ionization (APCI)|
|Applications||Forensics, environmental monitoring, drug testing, flavor profiling||Proteomics, drug development, metabolite profiling|
|Complexity & Maintenance||Moderate; maintenance due to column and MS conditions||Higher; potential column clogging and contamination|
|Resolution||High (dependent on column and instrument)||High (dependent on column and instrument)|
|Typical Uses||Drug testing, environmental pollutants, metabolomics||Biomolecules, peptides, pharmaceuticals, large organic molecules|
|Detector Sensitivity||High for volatile compounds||High, especially with modern detectors and for a broader range of compounds|
|Advantages||Effective for a wide range of volatile organic compounds, established method with well-defined libraries||Broad applicability, can handle larger and more diverse compounds|
|Limitations||Limited to volatile and thermally stable compounds, potential fragmentation upon ionization can complicate spectra||Potential for sample loss or degradation due to multiple steps, sensitivity can be affected by matrix effects|