1. What is targeted metabolomics and what are its advantages?
Targeted metabolomics utilizes chromatography-mass spectrometry (LC-MS) combined with authentic standards to perform absolute quantification of specific metabolites. It is particularly suitable for precise quantification and clinical validation. Its primary advantage lies in the accurate absolute quantification of known compounds, delivering highly reliable data.
2. What are internal standards and reference standards?
An internal standard (IS) is a substance that is not naturally present in the sample being tested; isotopically labeled standards or chemical analogs are commonly used. In targeted metabolomics, the internal standard method is used to normalize the peak area of the analyte in the sample, yielding a relative peak area for quantification. This process minimizes systematic errors and ensures the accuracy of the quantitative results. Additionally, internal standards serve to evaluate instrument stability: by calculating the dispersion of IS peak areas across different samples, researchers can assess the stability of the instrument and the reliability of the data.
A reference standard (or standard) corresponds directly to the analyte (the substance being tested). During the experiment, a series of standards with known concentration gradients are analyzed to establish the relationship between concentration and peak area, which is used to generate a standard curve. The peak area of the analyte in the sample is then mapped to this standard curve to calculate its absolute concentration and content.
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