-scan mass spectrum of Compound X.

From the spectrum in Figure 3, it is clear that compound X has an [M+H]+ ion at 579 and an [M+Na]+ ion at 601. The MS/MS spectrum of the [M+H]+ ion of Compound X (Figure 4) indicates a loss of 146 and also exhibits an ion of m/z 271the m/z of the [M+H]+ ion of apiginin. The loss of 146 is often indicative of the loss of a deoxy-hexose sugar and the m/z 271.1 ion is indicative of the base component: apiginin.

At this point it is possible to do MS³ on the 271.1 ion and compare the spectrum with that of the MS/MS spectrum of apiginin. Before we do this, however, we shall first endeavor to determine whether the m/z 271 ion is related to the m/z 433 ion. To accomplish this, an MS³ experiment was performed on the m/z 433 ion and the spectrum is illustrated in Figure 5. The hypothesis that the m/z 271 originated from the m/z 433 ion has been confirmed. The difference in the two masses (162 amu) is also indicative of the loss of a hexose sugar.


Figure 4. Full-scan MS/MS (m/z 579) mass spectrum of Compound X.



Figure 5. Full-scan MS3 (579>433>) mass spectrum of Compound X.



Figure 6. Full-scan MS4 (579>433>271>) mass spectrum of Compound X.

Up to now, the only evidence that Compound X belongs to the flavonoid class is the presence of the m/z 271 ion. This is far from compelling evidence. Compelling evidence would be achieved if the MS/MS of this m/z 271 ion yields a spectrum which is similar to the MS/MS spectrum of apiginin. This hypothesis is tested via the MS⁴ experime
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