ANALYTICAL
BIOCHEMISTRY
68,
658-659
An Inexpensive,
( 1975)
Efficient
Filtering
Manifold
Many analytic procedures are designed to trap radioactive materials on filters in order to determine the level of radioactivity of the washed filter pad by liquid scintillation counting. The methods include analysis of trichloracetic acid (TCA)-insoluble material, such as TCA-insoluble peptides synthesized in in vitro protein synthesis experiments, and the retention of specific complexes of proteins and ligands on filter paper, such as the absorption of tubulin- [ “H] colchicine complex onto diethylaminoethyl cellulose filter paper. For these and other purposes, an apparatus is needed to process many samples rapidly, with minimum contamination between samples. A variety of commercial apparatuses are available but generally are expensive. In addition, many are constructed with materials that are destroyed or weakened by commonly used solvents. Warping is a particular problem with filtering devices constructed with Lucite. An inexpensive manifold has been devised which will allow simultaneous vacuum filtration of several samples. The materials needed are easily available through local hardware or plumbing supply firms. Figure 1 shows the general construction of the apparatus. PVC pipe (3/4-in. AMOCO200 PSI PVC) is used throughout and glued with universal cement. Matching 3/4-in. PVC Tee’s are linked with short sections of 3/4-in. PVC tubing. Bends are made with a 90” L and one of the end Tee’s is rotated 90” to the outside as that a water aspirator vacuum line can be attached. Glass tubing was bent at 90” and inserted through the stopper in the vacuum line so the liquid level in the PVC tubing was kept at a low level. The number of filter ports can be increased to suit individual needs. The inner surface of the Tee has a shoulder approximately 1 in. from the end which supports a circular piece of 40-mesh stainless-steel wire screen or a 25-mm-diameter stainless-steel screen that can be purchased from Millipore Corp. (XX30 02510). Two-inch sections of 3/4-in. PVC pipe were slightly tapered on a lathe until they just fit tightly into the Tee and the ends faced. These sections are inserted into the Tee and firmly pressed down to anchor the outside edge of the filter paper to the wire screen. Twenty-five-millimeter-diameter filter papers or fiber-glass filters are used, but care must be taken to center the filter since it does not fit closely against the walls of the Tee. The fit is sufficiently good so that no leakage around the filter occurs. Unused filtering ports may be plugged with # 6 rubber stoppers. The PVC holds up well against trichloroacetic 658 Copyright @ 1975 by Academic Press, Inc. All rights of reproduction in any form reserved.
SHORT
659
COMMUNICATIONS
FIGURE
I
acid. Materials for the entire apparatus as shown costs about $5.00 or less than $30.00 if Millipore filter screens are used. KENNETH
L. L. Departmetlt Unitlersity Received
of Biochrmistry of Kansas, Law-ewe, February 25. 1975:
Kansas accepted
66045 April 24. 1975
OLSON
I-I~u~ToN
BIOCHEMISTRY
68,
658-659
An Inexpensive,
( 1975)
Efficient
Filtering
Manifold
Many analytic procedures are designed to trap radioactive materials on filters in order to determine the level of radioactivity of the washed filter pad by liquid scintillation counting. The methods include analysis of trichloracetic acid (TCA)-insoluble material, such as TCA-insoluble peptides synthesized in in vitro protein synthesis experiments, and the retention of specific complexes of proteins and ligands on filter paper, such as the absorption of tubulin- [ “H] colchicine complex onto diethylaminoethyl cellulose filter paper. For these and other purposes, an apparatus is needed to process many samples rapidly, with minimum contamination between samples. A variety of commercial apparatuses are available but generally are expensive. In addition, many are constructed with materials that are destroyed or weakened by commonly used solvents. Warping is a particular problem with filtering devices constructed with Lucite. An inexpensive manifold has been devised which will allow simultaneous vacuum filtration of several samples. The materials needed are easily available through local hardware or plumbing supply firms. Figure 1 shows the general construction of the apparatus. PVC pipe (3/4-in. AMOCO200 PSI PVC) is used throughout and glued with universal cement. Matching 3/4-in. PVC Tee’s are linked with short sections of 3/4-in. PVC tubing. Bends are made with a 90” L and one of the end Tee’s is rotated 90” to the outside as that a water aspirator vacuum line can be attached. Glass tubing was bent at 90” and inserted through the stopper in the vacuum line so the liquid level in the PVC tubing was kept at a low level. The number of filter ports can be increased to suit individual needs. The inner surface of the Tee has a shoulder approximately 1 in. from the end which supports a circular piece of 40-mesh stainless-steel wire screen or a 25-mm-diameter stainless-steel screen that can be purchased from Millipore Corp. (XX30 02510). Two-inch sections of 3/4-in. PVC pipe were slightly tapered on a lathe until they just fit tightly into the Tee and the ends faced. These sections are inserted into the Tee and firmly pressed down to anchor the outside edge of the filter paper to the wire screen. Twenty-five-millimeter-diameter filter papers or fiber-glass filters are used, but care must be taken to center the filter since it does not fit closely against the walls of the Tee. The fit is sufficiently good so that no leakage around the filter occurs. Unused filtering ports may be plugged with # 6 rubber stoppers. The PVC holds up well against trichloroacetic 658 Copyright @ 1975 by Academic Press, Inc. All rights of reproduction in any form reserved.
SHORT
659
COMMUNICATIONS
FIGURE
I
acid. Materials for the entire apparatus as shown costs about $5.00 or less than $30.00 if Millipore filter screens are used. KENNETH
L. L. Departmetlt Unitlersity Received
of Biochrmistry of Kansas, Law-ewe, February 25. 1975:
Kansas accepted
66045 April 24. 1975
OLSON
I-I~u~ToN
