Diode-array detectors , carotenoid separation

This method requires the least sophisticated equipment and relies heavily on the unique characteristics of the column to separate the carotenoids (Craft et al., 1992 Epler et al., 1992). It incorporates the use of a polymeric Cl 8 column, which has been shown to offer unique selectivity for structurally similar compounds such as geometric isomers. The addition of a second detector or use of a diode-array detector permits the simultaneous analysis of tocopherols, but not retinol. If the method is modified to incorporate a solvent gradient, retinol can be measured also (MacCrehan and Schonberger, 1987). 

Carotenoid retention and separation are influenced by column temperamre at temperatures above 20-25°C, lutein and zeaxanthin may not be well separated. Tocopherols can be measured simultaneously by using a diode array detector, a second UV detector set at 280-300 nm, or a fluorescence detector set at 296 nm excitation and 336 nm emission. 

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