Portal de Periódicos da CAPES

Comparative chromatography of the chloroplast pigments

1968; Elsevier BV; Volume: 24; Issue: 1 Linguagem: Inglês

10.1016/0003-2697(68)90059-6

1096-0309

H. H. Strain, Joseph Sherma, M. Grandolfo,

Dye analysis and toxicity

Many conditions influence the separability of the chloroplast pigments by chromatography. These conditions include the nature and treatment of the sorbent, the solvent or wash liquid, the form in which the sorbent is employed, and the loading of the sorbent with the mixture. Various adsorbents exhibit different capacities and selectivities for the pigments, and they often provide different sequences of the separated pigments. Some adsorbents, such as magnesia, exhibit variation of capacity and selectivity when made into a thin layer from a slurry with water. Very finely divided adsorbents, such as activated magnesia, may be employed both in columns and in thin layers if mixed with a nonsorptive filter aid. With all the chromatographic systems that were tested, the lower the initial loading with the mixture, the greater is the resolution. Conversely, the higher the loading, the poorer is the resolution. Both with underloading and overloading, minor constituents may not be detectable. Readsorption of large fractions of the pigments obtained from one chromatographic system improves the separation and the detection of the minor leaf pigments. Readsorption with a different chromatographic system permits the separation of pigments, such as lutein and zeaxanthin, and α- and β-carotene, that were inseparable in the first system. For these chromatographic and rechromatographic procedures, columns are much more adaptable than thin layers and sheets of the adsorbent. For the preparation of quantities of the leaf pigments, columnar methods are more convenient than thin-layer and paper techniques. The separations in columns are faster and more adaptable than separations in thin layers or in paper. The major pigments of cocklebur (Xanthium) are chlorophylls a and b, neoxanthin, violaxanthin, lutein, and β-carotene. The minor pigments are cryptoxanthin, zeaxanthin, trace amounts of α-carotene and lutein epoxide, and possibly minute traces of zeaxanthin monoepoxide (antheraxanthin).