Chromatography, centrifugal thin layer

The neutral lipid fraction from the DEAE-Sephadex A-50 column was combined with the lower phase obtained after Folch partition of the total lipid extract and the combined lipids dried. To the same flask, 10Q ml of 0.6 M NaOH in methanol was added. The mixture was incubated at 37°C for 5 hours. Five volumes of acetone were then added and stored overnight at 4°C. The precipitate was collected by centrifugation at 4°C and dissolved in C M (4 1, v/v). After application to the column (2.0 x 25 cm), the column was washed with chloroform. Neutral glycolipids were then eluted with tetrahydrofuran H2O (10 1). Fractions containing neutral glycosphingolipids were pooled and their glycolipid content examined by thin-layer chromatography. 

The fatty acid composition of lipids is usually analyzed by gas chromatography following transesterification into methyl esters. Unmodified lipids can be analyzed by HPLC or by soft chemical ionization mass spectrometry. In the course of sample preparation it is often necessary to separate the various membrane fractions (plasma membrane, thylakoid, microsomal, mitochondrial, etc.) by sophisticated gradient centrifugations, as well as the individual lipid classes within a membrane fraction, usually by thin-layer chromatography (TLC). 

The milk and cream were centrifuged, and the fat fraction was removed. The fat was extracted with carbonyl free hexane, and the fat extract was immediately reacted with 2,4-dinitrophenylhydrazine. The carbonyl compounds formed respective 2,4-dinitrophenylhydrazones (2,4-DNPH). The hydrazones were separated into monocarbonyls and then further purified using thin layer chromatography (18). Alkanal 2,4-DNPH were analyzed by gas chromatography using a 1.83 m glass column (i.d. 4 mm) packed with 2% OV-1 on acid washed Chromosorb W ( 180-200 mesh) (18,19). ... 

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