Should Glucose be Detected Using Positive or Negative Ion Mode in Liquid Chromatography-Mass Spectrometry?
When glucose is detected using liquid chromatography-mass spectrometry (LC-MS), positive ion mode is generally preferred. This is because carbohydrates, such as glucose, are more likely to ionize in positive ion mode and typically exhibit higher signal intensity and sensitivity.
In positive ion mode of LC-MS, glucose molecules can acquire a positive charge by forming adducts with metal ions (such as sodium or potassium) or through other ionization mechanisms. This enhances their detectability in the mass spectrometer. However, it is important to note that the ionization efficiency of carbohydrates is usually lower compared to other organic compounds. Therefore, the experimental conditions-including the pH of the mobile phase, the type and ratio of organic solvents, and the ion source parameters-must be carefully optimized to achieve optimal detection performance.
In certain cases, such as when employing specific derivatization strategies or addressing unique analytical requirements, negative ion mode may also be utilized. However, for most carbohydrate analyses, particularly monosaccharides like glucose, positive ion mode remains the preferred choice.
MtoZ Biolabs, an integrated chromatography and mass spectrometry (MS) services provider.
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