Page 264 - Natural Antioxidants, Applications in Foods of Animal Origin

Methods and Their Applications for Measuring 243
VetBooks.ir

GC

MS

FIGURE 6.30 GCMS is the combination of gas chromatography and mass spectroscopy
(GCMS). When used in combination, one or several types of compounds from lipid oxidation
can be measured.

Using the read-out from the recorder, the concentration of the marker
compounds can be calculated using the following steps.

1. A known amount (usually1 µL) of an appropriate standard is injected
into the column.
2. Although peak measurement for chromatographic quantitative anal-
ysis has been computerized, the areas of peaks in the diagram have
been calculated.

Area of eluted peak (mm ) = (ht. of peak) × (peak w at 0.5 × h) (6.17)
2
(0.5 x h to reduce error from “tailing” at the base of the peak)

3. The peak from 1 μL of the standard is 101.5 mm; therefore, the
concentration of the eluted marker compound(s) can be calculated
(Table 6.7).
4. The separated compounds exiting the GC are bombarded by a high
energy electron to produce charged particles necessary of mass
analysis.

CH (CH ) CHO + 1 e CH (CH ) CHO + 2 e –
–
+
2 4
3
2
3
4
(hexanal from GC) (electron beam) (+charged particle for mass analysis)