What is it?
What does GC-MS stand for?
Gas Chromatography-Mass Spectrometry
What is Step 1?
Sample Preparation – Biological samples (e.g., blood, urine, tissues, or cell extracts) are processed to extract metabolites. In many cases, derivatization (chemical modification) is required to make non-volatile compounds suitable for GC analysis.
How does the combination of gas chromatography (GC) and mass spectrometry (MS) make GC-MS one of the most precise and reliable tools for metabolite analysis?
High Sensitivity & Specificity—Can detect metabolites at very low concentrations.
Why does GC-MS require derivatization for the analysis of many biological metabolites like amino acids and sugars?
Requires Derivatization—Many biological metabolites (e.g., amino acids, sugars) need chemical modifications before analysis.
What is GC-MS Metabolomics used for?
It is used for to identify and quantify small molecules in biological samples.
What is Step 2?
Injection & Vaporization—The processed sample is injected into the gas chromatograph, where it is rapidly heated and converted into the gas phase. This ensures that all metabolites can be efficiently carried through the GC column by an inert carrier gas (e.g., helium or nitrogen).
Why is GC-MS suitable for analyzing a wide range of volatile and semi-volatile metabolites?
Comprehensive Analysis—Suitable for analyzing a wide range of volatile and semi-volatile metabolites.
Why is GC-MS limited to volatile compounds, and how does this affect the analysis of non-volatile metabolites?
Limited to Volatile Compounds—Non-volatile metabolites may not be effectively analyzed without prior modification.
What does GC-metabolomics separate?
GC separates complex mixtures of metabolites with mass spectrometry
What is Step 3?
Gas Chromatography (GC) Separation – The vaporized sample passes through a GC column, where metabolites are separated based on their volatility and interaction with the stationary phase of the column. Less volatile compounds take longer to travel through the column, while more volatile compounds exit faster.
What makes GC-MS a robust and reproducible technique, making it ideal for large-scale studies?
Robust & Reproducible – Produces highly reproducible results, making it ideal for large-scale studies.
How does the extensive preprocessing, including derivatization, contribute to the time-consuming nature of GC-MS sample preparation?
Time-Consuming Sample Preparation—Extensive preprocessing steps, including derivatization, can make sample analysis slower.
What is Step 4?
Ionization & Mass Spectrometry (MS) Detection—The separated metabolites enter the MS detector, where they are ionized (e.g., via electron ionization), fragmented, and analyzed based on their mass-to-charge (m/z) ratios. Each metabolite produces a unique fragmentation pattern (mass spectrum), which helps in its identification.
How do well-established databases like NIST, METLIN, and HMDB enhance the accuracy of metabolite identification in GC-MS?
Well-Established Databases—GC-MS has extensive libraries (e.g., NIST, METLIN, HMDB) for accurate metabolite identification.
Why is GC-MS considered a destructive analysis technique, and how does this limitation impact further testing on the same sample?
Destructive Analysis—Samples cannot be recovered after GC-MS analysis, limiting the ability to perform additional tests on the same sample.
How does the combination of gas chromatography (GC) and mass spectrometry (MS) make GC-MS one of the most precise and reliable tools for metabolite analysis?
Combination of Two Powerful Techniques—It integrates gas chromatography (GC) for separating metabolites and mass spectrometry (MS) for identifying them, making it one of the most precise and reliable tools for metabolite analysis.
What is Step 5?
Data Processing & Metabolite Identification—The detected mass spectra are compared with known databases (e.g., NIST, METLIN, or HMDB) to identify metabolites. Advanced bioinformatics tools are used to analyze metabolic pathways and identify differences between sample groups.
In what ways does GC-MS provide absolute or relative quantification of metabolites, enabling detailed metabolic profiling?
Quantitative Capabilities—Can provide absolute or relative quantification of metabolites, allowing for detailed metabolic profiling.
How does GC-MS's limited coverage of polar and thermally unstable metabolites affect its effectiveness in certain metabolomics studies?
Limited Coverage of Certain Metabolites—Polar and thermally unstable metabolites may not be well-detected using GC-MS, making it less effective for some metabolomics studies.