LC-MS/MS are the combination of liquid chromatography (LC) with mass spectrometry (MS). MS means you only analyze your precursor ion (as generated in the source) for example in an iontrap, a quadrupole or time-of-flight Massspec. MS/MS is the combination of two mass analyzers in one mass spec instrument. The first MS filters for the precursor ion followed by a fragmentation of the precursor ion with high energy and e.g. nitrogen gas. A second mass analyzer is then filtering for the product ions, generated by the fragmentation. This is usually done in a triple quadrupole MS (QQQ) or a QTOF. The advantages of MS/MS is the increased sensitivity (in the QQQ, due to reduction of noise) and you can gain more structural information on your analyte (QTOF) based on the fragmentation pattern. |