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Composition of tomatoes and tomato products in antioxidants (WG1) page 86
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1996). However TEA concentration must not exceed 0.1 % in the mobile phase because
tailing process occured on peaks leading to misquantification.
Of course, the mobile phase was shown to influence the separation efficiency of the
different peaks but it can also modify the carotenoid recovery. Hence methanol or buffered
acetonitrile mobile phase produced the higher recoveries (Epler et al. 1993). Switching from
an unbuffered acetonitrile-based mobile phase to a methanol-based phase gave the most
striking increase in recovery (Fig 21).
Fig 21. Total recovery of a mixture of plasma carotenoids from 64 commercially
available reverse phase columns using methanol and acetonitrile based mobile phases.
(From Epler et al; 1993)
The metal frits of HPLC columns were thought to increase recrystallization or to
increase oxydative degradation of carotenoids during analysis (Scott 1992). Replacing metal
frits by metal free biocompatible (teflon or ceramic) frits resulted in a reduction of minor
contaminant peaks and an increase of the peak response (Fig 20).
Finally, Scott (1992) reported that interactions between carotenoids, injection solvents
and mobile phase can result in peak distortion and the production of artefacts which can lead
to misinterpretation of the chromatogramm. Depending on the nature of the injection solvent,
single or multiple peaks can be produced from a single compounds (Khachick et al. 1988).
Hence we observed that THF solubilized very well the dry residue of the extraction organic