Screening funnel

FIGURE 28.1 The screening funnel. Loss of compounds is to be expected as candidates proceed through the preclinical process. 

Genaic screening funnel High throughput screening... 

The basin A is then gently heated by a small Bunsen flame, which should be carefully protected from side draughts by screens, so that the material in A receives a steady uniform supply of heat. The material vaporises, and the vapour passes up through the holes into the cold funnel C. Here it cools and condenses as fine crystals on the upper surface of the paper B and on the walls of C. When almost the whole of the material in A has vaporised, the heating is stopped and the pure sublimed material collected. In using such an apparatus, it is clearly necessary to adjust the supply of heat so that the crude material in A is being steadily vaporised, while the funnel C does not become more than luke warm. 

To a solution of 33 g. (O.S mole) of potassium hydroxide (Note 1) in 1.5 1. of distilled water in a 5-1. flask or other appropriate container fitted with a mechanical stirrer is added 80 g. (0.5 mole) of methyl hydrogen adipate (Note 2). With continuous stirring a solution of 85 g. (0.5 mole) of silver nitrate in 1 1. of distilled water is added rapidly (about IS minutes). The precipitated methyl silver adipate is collected on a Buchner funnel, washed with methanol, and dried in an oven at 50-60°. For the next step the dried silver salt is finely powdered and sieved through a 40-mesh screen. The combined yield from two such runs is, 213 g. (80%). 

Sand Content. The sand content in mud is determined using a 200-mesh sieve screen 2 in. in diameter, a funnel to fit the screen, and a glass measuring tube. The measuring tube is marked for the volume of mud to be added to read directly the volume percent of sand on the bottom of the tube. 

I placed a weighed quantity of sodium borohydride in a flask and attached it to a dropping funnel which contained water. The outlet from the flask was connected to a gas meter. The entire assembly was placed behind an explosion screen, since I did not know how violent the reaction might be. 

A funnel with a clamped rubber tube on the stem is placed in a ring stand. A circular mesh screen is placed across the funnel approximately one-third from the top, a portion of coarse fabric such as muslin is placed on the screen, and feces is added. Tap water at 37°C is added so that the water just touches the feces. Let the specimen stand 1 h, remove 2 ml of fluid from the stem, and centrifuge the sample at 300 x g for 3 min. Prepare a wet mount of sediment, and examine it for larvae. 

Sand as diluent to prevent caking, 33,98 Saponification, of ethyl linoleate, 32, 78 of ethyl linolenate, 22, 84 of natural oils, 22, 75, 79, 82 Screen, protective, 22, 97 Seal, rubber tube, for stirrer shaft, 21,40 Senecioic acid, 23, 27 Separatory funnel, large, construction of, 23,10S... 

The equipment feed design consisted of a funnel-shaped powder hopper (with no vacuum deaeration system) that was located directly above the rolls. The powder hopper was retrofitted with vacuum deaeration capability. A high compression feed screw, fitted inside the funnel hopper, fed the powder directly into knurled rolls. The compaction trials were conducted with and without vacuum deaeration. The compact was carefully collected directly on a 10-mesh screen. Powder particles, that were not compacted (i.e., those particles which were not attached to the compact, for example, fines bypassing roll compaction and the non-adhering compacted powder particles) were weighed and separated. The compact was not milled. The parameters are noted in Table 4. 

Often one will try to make sure that the sample is not the shape of the funnel, i.e., a cylinder-shaped sample is not desired, as some air space between the funnel and the sample is needed so that the liquid does not travel through the sample. Ideally, the top of the sample should be shaped so that any liquid will run off. Often a wire or screen is used to hold the sample so that moisture can drain. 

To 20 gms. (1 mol.) of cold boiled-out 67% nitric acid, 2 gms. of urea in 15 gms. (excess) of absolute alcohol are added, and half of the mixture distilled off on a water bath in a tubulated retort attached to condenser and receiver. 40 gms. of similar nitric acid mixed with 30 gms. of absolute alcohol, and containing 0-5 gm. of urea, are now allowed to drop in through the tubulus from a tap funnel at the same rate as the liquid distils. Water is added to the distillate, the ester which separates is washed several times with cold water, dried over calcium chloride, and distilled from a water bath, the fraction 84°—88° being retained. Care must be taken in this experiment, as the ester is liable to explode when quickly heated. All operations should be carried out behind a metal screen. 

Aqueous samples are extracted with methylene chloride using a separatory funnel or a continuous liquid-liquid extractor. Solid samples are extracted with methylene chloride-acetone mixture (1 1) by either sonication or Soxhlett extraction. The methylene chloride extract should be finally exchanged to hexane or iso-octane or methyl tert-butyl ether. The latter solvents should be mixed with acetone during solvent exchange. The extracts should then be cleaned up by Florisil. Often Florisil cleanup reduces the percent recovery of analyte to less than 85%. A preliminary screening of the extract should, therefore, be done to determine the presence of interference and the necessity of florisil cleanup. Gel permeation cleanup also lowers the analyte recovery and thus is not recommended. If a FPD is used in the GC analysis, the presence of elemental sulfur can mask the analyte peaks. In such a case, sulfur cleanup should be performed. Sample extraction and cleanup procedures are described in Chapter 1.5. 

Example of a protected amine. The protected amino acid V -ferf-butoxy carbonyl (Boc)-l-lysine, when used as the amine to synthesize the triazine-based ligands, is deprotected prior to screening with protein. Protected immobilized ligands, after washing with the appropriate solvent in a sintered funnel, are immersed in 99% v/v trifluoroacetic acid (TFA) and stirred for 1 h in the fume hood. Methanol is added to dilute the TFA, and the waste solution is carefully disposed of. The matrixes are washed sequentially with methanol and distilled water (3 10 gel... 

Pollucite is ground to 120 mesh as described in procedure B above. One hundred grams of the screened material is mixed with 400 ml. of concentrated hydrochloric acid (12 M) in a 1-1. round-bottomed flask, which is connected to a reflux condenser, and refluxed gently for 30 hours. The resulting solution is filtered with suction, using a large Buchner funnel, and the silica residue is washed with about 150 ml. of water. 

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