Detection of cis-trans carotene isomers by two-dimensional thin-layer and high-performance liquid chromatography

Abstract

High-performance liquid chromatography (HPLC) was used to detect cis-trans isomers of a-and /3-carotene. Monitoring HPLC eluants at both 436 and 340 nm and calculating the peak height ratio, 340 nm/436 nm, permit detection of isomers in carotene-petroleum ether solutions and plant extracts. Separation of individual isomers was achieved on thin-layer chromatography (TLC) plates prepared with calcium hydroxide layers. Equilibration of the plates to 44% relative humidity prior to development with 1.5% p-methylanisole in petroleum ether was necessary to achieve optimal resolution. No isomeric carotenoids were found in the fresh yellow-orange vegetables, but analyses of chlorophyll-containing vegetables indicated that isomers were present. Heat-processed products contained a variety of cis isomers. Sample handling, saponification methods, and sample pH did not influence the formation of isomers.

Carotenes in typical and dark orange carrots

“…No peak was found in carrot samples with a retention time similar to that of the internal standard (none closer than 0.3 min). These values are less than the values Schwartz and Patroni-Killam (1985) indicated as suggestive of isomerization. The p-zea-and {-carotene quantities from HPLC were estimated by multiplying observed peak areas by 0.85 and 3.7, respectively, since AM of @-carotene is approximately 85 % that of p-zeacarotene (Petzold et al, 1959) and approximately 3.7 times that of @-carotene (Zscheile and Porter, 1947).…”

“…However, inspection of absorption spectra suggested the presence of little or no cis isomers since the characteristic 300-360-nm "cis peak" (Sweeney and Marsh, 1971;Schwartz and Patroni-Killam, 1985) was not evident in samples from either column chromatography fractions or TLC bands. However, inspection of absorption spectra suggested the presence of little or no cis isomers since the characteristic 300-360-nm "cis peak" (Sweeney and Marsh, 1971;Schwartz and Patroni-Killam, 1985) was not evident in samples from either column chromatography fractions or TLC bands.…”

“…However, inspection of absorption spectra suggested the presence of little or no cis isomers since the characteristic 300-360-nm "cis peak" (Sweeney and Marsh, 1971;Schwartz and Patroni-Killam, 1985) was not evident in samples from either column chromatography fractions or TLC bands. This observation agrees with the reports of Schwartz and Patroni-Killam (1985) where processing increased the quantity of isomerized carotene severalfold. Yet we were able to note a distinct "cis peak" (-3% the height of the absorption maxima) in the a-and @carotene absorption spectra from a canned carrot sample (data not presented).…”

Evaluation of the Biochemical Composition of Four Marine Algae and Its Nutritional Value for Brine Shrimp.

“…The Artemia sp. nauplii enriched with the four different microalgae were studied for its carotenoid content by following the method of Schwartz and Patroni-Killam (1985). The amount of carotenoids extracted were scanned under UV visible spectrophotometer at 450 nm and further confirmed by TLC.…”

Lipophilic Vitamins

“…The (4). Ubiquinones Q-30, Q-35, Q-40, Q-45, Q-50 and vitamins K 2(30) , K 2( 3 5) , K 2 (45) , and K, were also separated on silica gel G impregnated with 5% paraffin oil in petroleum ether using acetone-water (95:5) mobile phase (143). Ubiquinones Q-30, Q-35, Q-40, Q-45, Q-50 and vitamins K 2(30) , K 2( 3 5) , K 2 (45) , and K, were also separated on silica gel G impregnated with 5% paraffin oil in petroleum ether using acetone-water (95:5) mobile phase (143).…”