Three-stage spray drying system

FIGURE 4.3 A schematic diagram of a typical three-stage spray-drying system. 

The phospholipase C of C. welchii (1 mg) in 0.5 M tris(hydroxymethyl)methylamine (tris) buffer (pH 7.5 2 mL), 2 x 10 M in calcium chloride, is added to phosphatidylcholine (5 mg) in diethyl ether (2 mL). After the mixture is shaken at room temperature for 3 hours, it is extracted three times with diethyl ether (4 mL portions). The ether layer is dried over anhydrous sodium sulfate before it is evaporated in a stream of nitrogen at ambient temperature. Pure 1,2-diacyl-sn-glycerols are obtained by preparative TLC on layers of silica gel G impregnated with boric acid (10 %, w/w), with hexane-diethyl ether (50 50, v/v) as solvent system. The appropriate band is located under UV light after spraying with 2, 7 -dichlorofluorescein (see Chapter 2), and is eluted from the adsorbent with diethyl ether. (Boric acid, which is also eluted, does not interfere with subsequent stages)."... 

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