Applications
| Targeted and untargeted | Targeted and untargeted | Targeted and untargeted | Targeted |
Strengths
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Robust and reproducible metabolite separation. Available databases to aid metabolite identification, for example, NIST. Quantitative analysis. Less expensive compared with other MS platforms.
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High resolution. Accurate mass determination. Thousands of metabolites detected in a single run. Fragment fingerprinting using MSn experiments. Derivatisation is rarely needed, though ionisation of the molecules is required.
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High specificity when combined with retention time. Quantitative analysis with the use of stable isotope labelled standards. Direct flow injection can be used with short run times, suited for targeted analysis of chemically related compounds. Derivatisation is rarely needed, though ionisation of the molecules is required.
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Challenges
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Low sensitivity compared with MS. Large sample volumes required compared with MS. Up to 200 metabolites can be detected in a single run due to overlapping signals compared with thousands detected in MS applications.
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Destructive technique. Relatively expensive compared with other MS techniques. Complex metabolite identification. Noise and redundancy in untargeted data. Lack of absolute quantification in untargeted applications. Low reproducibility, requiring quality control samples.
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