Chlorophylls solid-phase extraction

Ultrasound-assisted extraction provides efficient extraction in a shorter processing time than is needed for conventional extraction. The aid of ultrasound will result in a higher extraction yield and reduce solvent consumption. The extract may exhibit a wide range of colors (pale yellow, brown, red). For anthocyanin extraction in an acidic environment, the extract will be deep red, pink, or purple. The extract may contain considerable amounts of lipophilic compounds (e.g., chlorophyll, carotenoids, lipids). Prior to solid-phase extraction, those compounds can be eliminated from the extracts using liquid-liquid extraction. 

To obtain clear solutions, the extracts are either filtered or centrifuged and the residues reextracted with the same solvents (108). Another possibility is to transfer the chlorophylls from the acetone phase into an ether phase by adding sodium chloride (114) or sodium sulfate (93). More recently acetone extracts were purified and fractionated with C18 solid-phase extraction cartridges, and dephytylated pigments were eluted with 70% acetone and phytylated pigments with 90% acetone (115). Often a concentrating of the pigment solution with a rota-evaporator under vacuum is necessary before analysis. Chlorophyll extracts should be analyzed as soon as possible, but if they have to be stored they must be kept in the cold and dark (107). 

Portions of ground samples (25 g) were homogenized with 60 mL of acetonitrile and hltered. The hltrates were subjected to clean up using an ODS solid-phase extraction (SPE) cartridge (1 g). The acetonitrile was separated by salting-out and 36 mL were collected. After evaporation to dryness, the residue was adjusted to a volume of 3 mL in n-hexane-acetone (1 1). A 2-mL aliquot portion was loaded onto a PSA cartridge (200 mg) and eluted 3 times with 2 mL of n-hexane-acetone (1 1) to remove fatty acids and chlorophylls. All the eluates collected were evaporated to dryness and adjusted to a volume of 2 mL with n-hexane-acetone (4 1) for GC/MS analysis. A 0.4-mL aliquot of the hnal solution was evaporated and redissolved in 0.2 mL of acetonitrile for LC/MS analysis. The GC/MS and... 

Extraction and cleanup procedures usually require solid-phase extraction based on commercially available Cig cartridges, for instance, after liquid extraction with common organic solvents (methylene dichloride, chloroform, acetonitrile).This step appears to be necessary to remove most of the interfering components such as carotenoids or chlorophyls, which are highly abundant in plants. Table 1 gives a list of some of the mycotoxins which can be analyzed by... 

High performance liquid chromatography (HPLC) has been by far the most important method for separating chlorophylls. Open column chromatography and thin layer chromatography are still used for clean-up procedures to isolate and separate carotenoids and other lipids from chlorophylls and for preparative applications, but both are losing importance for analytical purposes due to their low resolution and have been replaced by more effective techniques like solid phase, supercritical fluid extraction and counter current chromatography. The whole analysis should be as brief as possible, since each additional step is a potential source of epimers and allomers. 

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