Vacuum manifold alternative

Solid-phase extraction (SPE) offers an alternative way for enrichment of chlorinated fatty acids. Akesson-Nilsson presented an aminopropyl-based SPE technique for enrichment of chlorinated FAMEs in a cell-culture medium and for previously silver nitrate and urea treated eel lipids. In this application, a 500-mg aminopropyl column was connected to a vacuum manifold and conditioned with 2 ml of hexane. After transesterified lipid samples in 0.2 ml of hexane were loaded, the column was first eluted with 6 ml of hexane and then with 4 ml of a solvent mixmre made of hexane-diethyl ether-dichloromethane (89 1 10). In this way, the majority of non-chlorinated FAMEs were removed in the first elution and chlorinated FAMEs enriched in the later elution. 

Rotary Drum Filters The rotaiy drum filter is the most widely used of the continuous filters. There are many design variations, including operation as either a pressure filter or a vacuum filter. The major difference between designs is in the technique for cake discharge, to be discussed later. All the alternatives are characterized by a horizontal-axis drum covered on the cylindrical portion by filter medium over a grid support structure to allow drainage to manifolds. Basic materials of construc tion may be metals or plastics. Sizes (in terms of filter areas) range from 0.37 to 186 m (4 to 2000 ft ). 

Fig. 4. Schematic vacuum system for metal atom reactions. X represents the stopcock or Teflon-in-glass valve. Satisfactory components (for a general discussion of vacuum line design see References 1 and 4) forepump, 25 L/min free air capacity diffusion pump, 2 L/sec main trap is removable and measures about 300 mm deep main manifold has a diameter of about 25 mm, stopcock or valve in manifold should be at least 10 mm substrate container is removable container with 1-2 mm Teflon-in-glass needle valve connected to bottom of container. Connection between this needle valve and the reactor may be 1/8 in. od. Teflon tubing is used. Alternatively, the substrate may be added as shown in Fig. 3.

Rotary oil pumps will provide a reliable vacuum down to about O.OlmmHg (at the apparams) and are thus one of the most valuable pieces of equipment in the lab. Ideally every research worker should have his/her own high vacuum pump, but in many cases cost prohibits this and pumps are shared. If a pump is shared, it is common to have it mounted on a trolley which has all the ancillary devices (traps, gauge etc.) mounted on it. Alternatively, a shared pump may be fixed in one place, but attached to a communal manifold, distillation set-up or other piece of apparatus. A good two-stage pump is suitable for most high vacuum requirements in an organic chemistry lab. 

Alternatively, a piece of high vacuum tubing can be used to connect the traps to a distillation apparatus, a double manifold (Fig. 4.4, Chapter 4), or any other piece of equipment. 

---