Carotenoids - Natural Products Chemistry: Sources, Separations, and Structures - page 120

Mass Spectrum

1000

800

600

400

200

0

0.0000 100.0000 200.0000 300.0000 400.0000 500.0000

FIGURE 11.4 The mass spectrum of carotene, indicating the MH+ ion and subsequent
fragment peaks.

(2) Sudan (used as an internal standard); (3) all- trans β-cryptoxanthin; (4) all- trans
β-crytoxanthin; (5) all- trans -β-zeaxanthin (see Section 11.3); (6-9) luteoxanthin iso-
mers; (10) all- trans -violaxanthin; (11) 9- cis -violaxanthin; (12) 13- cis - violaxanthin;
(13) cis -neoxanthin; and (14) all- trans -neoxanthin. The identification of each carot-
enoid can be confirmed by mass spectrometry (MS). As an example, the MS spec-
trum of β-carotene shown in Figure 11.4 reveals the molecular ion fragment, MH+,
and subsequent fragmentation to smaller ions, 14 mass units (CH2) apart.
β-Carotene has been isolated from other sources, including carrots and algae. In
the HPLC chromatograms shown in Figures 11.5 and 11.6, the cis / trans isomers of
β-carotene have been isolated using a C-30 bonded reverse phase stationary phase.
In the former case, the separation was much faster and the peaks are sharper.

3

1

4 5

2

0 10 20

Time (min)

FIGURE 11. 5 HPLC separation of carotenoids in carrots.