Spinach pigments

Chromatographic Adsorption of Pigment from Leaves.2—Immerse fresh leaves (3-4) of spinach in a mixture of 45 c.c. of petrol ether (boiling point 70°), 5 c.c. of benzene and 15 c.c. of methanol in a conical flask. Leave for one hour, remove the almost white residue by filtration at the pump, and wash with the same mixture of solvents. Transfer the liquid to a separating funnel and without shaking remove the methyl alcohol completely by repeated cautious washing with water. Then dry the solution over sodium sulphate. 

Fig. 2.132. Chromatogram of spinach, stored frozen until analysis by HPLC (A) and after acidifying the same pigment extract with 0.2ml M HC1 per 10 ml extract and exposure to air and light for 15 h at 20°C (B). Zinc-phtalocyanine was used as an internal standard (IS). Peak identification 1 = chlorophyll-b 2 = chlorophyll-a x = unknown degradation product 3 = IS 4 = pheophytin-b 5 = pheophytin-a 6 = chlorophyll-b 7 = chlorophyll-a 8 = pheophytin-b 9 = pheophytin-a. Reprinted with permission from T. Bohn et al. [303].

Carotenoids are pigments found in some fruits and vegetables, including spinach. 

The CP26 pigment-protein complex has been described in maize and spinach as having an intermediate chib content between CP29 and LHCII [8, 75,76]. Its pigment complement includes violaxanthin, lutein and neoxanthin as well as chla and chib in a 2.2 ratio [10]. Lower (1.8) and higher (2.7) a/b ratio... 

Physical Methods and Physical Chemistry.—Separation and Assay Methods. A procedure for h.p.l.c. of plant pigments has been used to separate the carotenoids of spinach and of a diatom. H.p.l.c. separations of citrus carotenoids, and of retinal (67) isomers have also been reported. Carotenoid mixtures have also been separated efficiently and rapidly by centrifugal chromatography. ... 

This experiment provides students with the opportunity to isolate a biomolecule from its natural source, followed by its purification and identification. In addition, students will follow a procedure that is typical of the general extraction and characterization of lipids. However, unlike most lipids, the plant pigments are highly colored and may be characterized and quantified by visible spectrophotometry. Several types of plant tissue may be used. Some recommendations are fresh leaves (tree, plant, grass, spinach), green algae, or mosses. For variety, students may be asked to bring their own samples for analysis. 

Chloroplasts will be isolated by careful extraction of spinach leaves, using tricine buffer containing sucrose. The crude extract contains both whole and fragmented chloroplasts, but both contain all the necessary photosyn-thetic components and are capable of photophosphorylation. The preparation described in this experiment retains almost all of the chlorophyll in the chloroplasts. The total chlorophyll content of the chloroplasts will be determined by extracting the pigment with aqueous acetone and measuring the absorption at A. = 652 nm. The chlorophyll concentration is calculated according to Equation E9.3 (Arnon, 1949),... 

Chlorophyll. Chemically pure chlorophyll is difficult to prepare, since it occurs mixed with other colored substances such as carotenoids. Commercially it is solvent extracted from the dried leaves of various plants such as broccoli or spinach. Chlorophyll is water-iosoluble. It has none of the characteristics of a dye in that it has no aflinity for the usual libers such as cotton or wool. Chlorophyll is properly classified as a pigment tCI Natural Green 3 Cl 75810), As such. It finds use lor coloring soaps, waxes, inks. fats, or nils. Chlorophyll is an ester composed of an acidic pint, chlorophyllin, esterilied by an aliphatic alcohol known as phylol. Hydrolysis of chlorophyll using sodium hydroxide produces the moderately water-soluble sodium salts of chlorophyllin. phytol. and methanol. The magnesium in chlorophyllin may be replaced by copper. The sodium copper chlorophyllin salt is heat-stable, and is ideal for coloring foods where heat is involved, such as in canning. 

Easter egg dyes are natural dyes that can be found around the home. They include blue from cabbage leaves or blueberries, orange from yellow onion skins, red from cranberries or raspberries, pale green from spinach leaves, and light yellow from orange or lemon peels. Dyes often have different colors in acidic and alkaline solutions. This enables them to be used as acid-base indicators. Many dyes are utilized as biological stains, see also Cosmetics Perkin, William Henry Pigments. 

Vitamin A, or retinol, is one of the major fat-soluble vitamins. It is present in many foods the best natural sources are liver, butter, margarine, egg yolk, carrots, spinach, and sweet potatoes. Vitamin A is the precursor of retinal, the essential component of the visual pigment rhodopsin. 

Isolation of Chlorophyll and Carotenoid Pigments from Spinach... 

For an introduction to thin layer and gravity column chromatography, we separate the pigments from frozen spinach. This is one green experiment that is literally green. A number of variations of this classic procedure have been reported (P). We have made only minor changes in the procedure of Pavia and co-authors 9d). However, since we obtain the UVA is spectrum of the carotene isolated from the spinach, implementation of this experiment facilitates a discussion of ultraviolet/visible spectroscopy. 

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