Separators filter for

Procedure Transfer 2.00 mL of each sample to separate test tubes, and equilibrate in the 37° water bath for at least 10 min. At the same time, equilibrate the Substrate Solution in the same water bath. At zero time, transfer 2.0 mL of the equilibrated Substrate Solution to the first sample tube, mix thoroughly, and return the tube to the 37° bath. Repeat the process for each sample. After exactly 30.0 min, transfer the test tube to a boiling water bath for 15 min, then remove and cool to room temperature. Add approximately 100 mg of Amberlite MB-1 Ion Exchange Resin to each tube, place the tubes on the shaker, and mix for at least 15 min. Filter the treated solution through a 0.45-p.m filter. Use a separate filter for each sample. Inject a 5-p.L portion of each filtered sample into a previously equilibrated high-performance liquid chromatograph equipped with an HPX 87C column (Biorad, or equivalent) and a differential refractometer. Filtered, degassed water is the mobile phase. Record the elution curve. 

Some plants have a separate filter for each sterile vessel. Others place filters in a central group which feeds all the vessels. In this case, one filter, for example, might be taken out of service each day, sterilized and put back into service. If there were ten filters in the group, each one would be sterilized every tenth day. This system has the advantage that the filter can be blown dry after sterilization with sterile air before it is put into service again. 

Acetylation. Heat i g. of />-nitrophenol with 5 ml. of an acetic acid-acetic anhydride mixture under reflux for 15 minutes. Pour into water the solid acetate separates. Filter, wash with water and re-crystallise from ethanol m.p. 77 5°. This treatment usually leaves o-nitrophenol unchanged. The addition, however, of about 0 5 ml. of cone. H2SO4 to the acetylating mixture gives the o-derivative, m.p. 40°. 

Oximes (compare Section III,74,B). The following procedure has wide application. Dissolve 0-5 g. of hydroxylamine hydrochloride in 2 ml. of water, add 2 ml. of 10 per cent, sodium hydroxide solution and 0-2 g. of the aldehyde (or ketone). If the latter is insoluble, add just sufficient alcohol to the mixture to give a clear solution. Heat the mixture under reflux for 10-15 minutes, and then cool in ice. If crystals separate, filter these off, and recrystallise from alcohol, dilute alcohol, benzene or light petroleum (b.p. 60-80°). If no solid separates on cooling, dilute with 2-3 volumes of water, filter the precipitated sohd, and recrystallise. 

The filter usually has an endless cloth, traveling intermittently between the plates via roUers, to peel off cakes. Unfortunately, if the cloth is damaged anywhere, the whole cloth must be replaced, which is a difficult process. Each time the filter cloth zigzags through the filter, the filtering direction is reversed this tends to keep the cloth clean. Most of these filters incorporate membranes for mechanical expression, and cakes sometimes stick to the membranes and remain in the chamber after discharge. Some vertical filters are available with a separate cloth for each frame. The cloths maybe disposable and such filters are designed to operate with or without filter aids. 

An on-line concentration, isolation, and Hquid chromatographic separation method for the analysis of trace organics in natural waters has been described (63). Concentration and isolation are accompHshed with two precolumns connected in series the first acts as a filter for removal of interferences the second actually concentrates target solutes. The technique is appHcable even if no selective sorbent is available for the specific analyte of interest. Detection limits of less than 0.1 ppb were achieved for polar herbicides (qv) in the chlorotriazine and phenylurea classes. A novel method for deterrnination of tetracyclines in animal tissues and fluids was developed with sample extraction and cleanup based on tendency of tetracyclines to chelate with divalent metal ions (64). The metal chelate affinity precolumn was connected on-line to reversed-phase hplc column, and detection limits for several different tetracyclines in a variety of matrices were in the 10—50 ppb range. 

Clear-Hquor advance reduces the quantity of Hquor that must be processed by soHd—Hquid separation equipment (for example, a filter or a centrifuge). The reduction in Hquor flow through the separation equipment may allow use of smaller equipment for a fixed production rate or increased production through fixed equipment. 

FIG. 18-109 Filter-aid filtration system for precoat or body feed. (Schweitzer, Handbook of Separation Techniques for Chemical Engineers, p. 4-12. Copy-light 1979 hy McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.)... 

When continuous lubrication is called for, the couplings should be supplied witli oil filtered to a minimum of 2 microns. Experience shows that filtering to K micron is possible and desirable. Usually this is done with a separate filter however, the whole system may be filtered to this level. The oil quantity furnished, per gear mesh, should be 3 gpm minimum. 

For purification the acid is crystallized from about 150 cc. of glacial acetic acid, using an acid-resistant filter for the hot solution (Note 7). Aconitic acid separates as small, colorless needles weighing 50-60 g., and about 10 g. more can be secured by concentrating the mother liquor under reduced pressure to one-third of its volume. The material is dried in the air and then in a desiccator containing sodium hydroxide in order to remove all traces of acetic acid. One crystallization usually is sufficient to bring the point of decomposition to 198-199° (Note 6). 

The oil separation, cooling and filtering for a twin-screwcompressor adds to the complexity of an otherwise simple machine. Some commercial screw compressors are available which have the oilhandling circuit built into the assembly, with a small loss of overall efficiency. 

It is very simple to perform batch fermentation in a small flask with a volume of say 200 ml. Now our target is to use a 2 litre B. Braun fermenter. All accessories are shown in Figure 10.5. The fermentation vessel only, as shown in Figure 10.6, with about 250 ml of media without any accessories but with some silicon tubing attached with a filter for ventilation is autoclaved at a 131 °C for 10 minutes at 15psig.9 After that, the system is handled with special care and all accessories attached. Media is separately sterilised and pumped into the vessel. Inoculum is transferred and the batch experiment is started right after the inoculation of seed culture. An initial sample is withdrawn for analysis. 

Electromagnetic separators sometimes are used as filters for the removal of ferromagnetic iron oxide from condensate and thus prevent it from being transported back to the boiler. 

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