Filter-paper tape

Filter measured volume of air through lead-acetate-impregenated filter paper tape compare optical density with unexposed impregnated spot of similar area. Lead-acetate-impregnated filter paper tape No data NR EPA 1978... 

Filter-Paper Tape. A technique that inherently conserves the sample uses a filter-paper roll. The sample would be deposited at a collecting station and then advanced to a measuring station. Ultimately, it wouM be wound onto a takeup reel and saved for further investigation. 

Figure 5. Proposed system for measurement of aerosol collected on continuous filter-paper tape.

Aerosol monitor(s), automatic concentration range problems, 64 concepts, 63 data storage, 62 filter-paper tape, 66-67 flow conditions, varying, 65 isokinetic flow, 64 sample manipulation, 66 sampling time, 65-66... 

Nearly 23 years of hourly observations on particulate matter concentrations have been collected at downtown Los Angeles and at six other sites in the Los Angeles area using a tape sampler calibrated to read in Km units. The design of these samplers is as described by Hall (20). Ambient air is drawn through a one square-inch (5.07 cm ) area of filter paper at a rate of 25 ft per hour (11.8 1pm) for 51.5 min of each hour. The darkness of the spot developed on the filter is measured by the ratio of the intensity of the reflected light from clean white filter paper, R, to reflected light from the aerosol deposit, R. As used by tfie air pollution control district, the Km unit is related to reflectance by the formula (21). 

Figure 2. Canula filter. The Teflon tubing is inserted through the NMR tube septum. The filter paper is taped onto the pyrex tubing using Teflon tape.

Dried blood spots (3 mm) are punched from filter paper cards (Whatman 903 paper, Whatman) and distributed in a microtiter plate. Each patient sample is run in duplicates. Subsequently, 100 pi of substrate buffer and 100 pi of citrate buffer are added to each specimen. The plate is shaken for 45 min, sealed with tape, covered with aluminum wrapping and incubated at 37°C for 21 h. The reaction is terminated by the addition of 200 pi stop solution and the fluorescence is read with an excitation wavelength of 365 nm and an emission wavelength of 450 nm. 

Approximately 7% of electric power in the United States goes into electrolytic chemical production. The electrolysis apparatus pictured here consists of a sheet of A1 foil taped or cemented to a wood surface. Any size will work, but an area about 15 cm on a side is convenient for a classroom demonstration. Tape to the metal foil (at one edge only) a sandwich consisting of filter paper,... 

Figure 1. Block diagram of single-photon time-correlation apparatus from Barker and Weston 11 HV, high-voltage supplies L, lamp PI, photomultiplier M, monochromator FURN, furnace C, sample cell LP, light pipe F, interference filter P2, photomultiplier AMP, amplifier DISCI, discriminator D1SC2, discriminator T-S, timer scaler DL, delay line TAC, time-to-amplitude converter BA, biased amplifier MCPHA, multichannel pulse-height analyzer TTY, teletype printer and paper-tape punch REC, strip-chart recorder.

Workers associated with the application of carbaryl (applicator, mixer-loader, bystander and aerial flagger) and re-entry workers (apple thinners) were monitored by a modification of the procedure of Durham and Wolfe (3). The workers were fitted with a disposable jacket (Safety and Supply Co., Seattle, WA) to which 10 x 10 cm pads were attached with masking tape. One pad was attached as close to the neck as possible on each shoulder and on the chest and the back of each subject. One pad was also placed on each forearm midway between the elbow and wrist. The pads were constructed by backing an 8 ply gauze compress with two pieces of heavy filter paper and attaching these together in the center with a staple. 

In paper chromatography we use filter paper, marketed for this purpose. It comes usually in the form of a 2-5 cm-wide tape, from which a strip of the necessary length can easily be cut. The more modern technique of thin layer chromatography (TLC), makes use of thin sheets of aluminium oxide, silica-gel, cellulose or some other material, supported by a metal sheet or a polymer. Chromatographic thin layers can be prepared in the laboratory from commercially available adsorbents. A thick suspension of these is made with water (usually a 2 1 w/w mixture of water adsorbent is made up) and this is then spread on a metal plate with a suitable spreader device. Techniques vary from device to device, and the instructions of the manufacturer should be followed whenever thin layer plates are to be prepared. Ready-made thin layer sheets are also available commercially. These contain the active material spread on a plastic support. Thin-layer chromatographic materials, especially ready-made plates, are much more expensive than chromatographic paper, but normally offer faster and sharper separations than the paper. The procedures described in Section VI.20 can be carried out both on a slow chromatographic paper (e.g. Whatman No. 1) or on a cellulose thin layer (e.g. Whatman cellulose). 

The sintered disc of the filter stick should be of porosity 3 or larger in order to avoid blockage. A convenient alternative to a filter stick is to use an ordinary glass rod with filter paper wrapped round the end (Fig. 11.4b). Wrap some Teflon tape round the end of the tube, then carefully fold filter paper over the end and secure it with wire. The Teflon tape will give a better seal because the wire will sink into it. Another alternative, for smaller scale work, is to use a long syringe needle (Fig. 11.4c). Again, the end of the... 

When glass fiber paper tape is used, this can be strengthened by the application of a rubber solution along each edge, or with an under tape of strong filter paper having coarse filtration properties. After drying, the tape must be sealed on the upper surface with transparent cellulose tape. 

Two other filtration modules, which both formed part of automated radioimmunoassay systems, have been developed. - One of these, was based on conventional continuous flow techniques. At the filtration stage, a continuously moving strip of glass fiber filter paper was strengthened and wetted, the reaction mixture was filtered, and the precipitate was washed by two streams of buffer. The strip was dried and overlaid with cellulose adhesive tape before being counted as it passed between two end-window radioactivity detectors and wound onto a take-up spool. In the second system, glass fiber filter disks are mounted at intervals over perforated segments of a flexible plastic carrier tape. The contents of five... 

Filter-Tape Method. A filter-tape system may be envisaged for automating even the 50-fxL method. An automatic tape system for collection of aerosols on filter paper was discussed earlier. The concept could be used here to transport samples to a drying chamber and then to an electrochemical cell where the sample is remoistened with a known volume of ionic-strength adjuster and measured by pressing the opposed electrodes together as shown in Figure 5. The paper must be pretreated by addition of hydro-phobic barriers to confine the sample to the desired area of the paper. All of these steps could be automated under control of the microprocessor. 

By the way, sometimes the indoor humidity doesn t vary much over a week s time. If you find this to be the case, you can create artificial humidity swings by using a 10- or 20-gal fish tank that has a 1-in. deep layer of water on the bottom. If you place the filter papers inside the fish tank (perhaps taped to the side and place the humidity meter in the fish tank, too) and cover it, you can create higher humidity values. 

Filter Stick. A typical filter stick for solution filtration is shown in Figure 4. A section of teflon tubing (2-3 ft) is pushed over the Luer fitting of an observation port (Popper Sons), and conventional filter paper is then attached to the end of the observation port as shown. Half inch teflon sealing tape (Aldrich - this may also be available from a local plumbers supplier as pipe dope) is first wrapped around the base of the observation port, filter paper is then wrapped around the outside of the teflon tape, and one or two loops of nichrome wire (20 gauge, 32 thou) are used to secure the filter paper in place. The teflon tape provides a bed into which the wire can bite and seal the system. Any filter paper may be used, but we have found water resistant fine filter papers such as Whatman s 50 to be most satisfactory, except for gummy solids which may require a faster paper. 

Material Beaker, voltmeter (multimeter), electric motor, cable and alligator clips, filter paper and adhesive tape zinc plate, graphite rod, manganese dioxide powder (Mn02), ammonium chloride solution. 

Procedure Fill a beaker two-thirds with the salt solution, attach a zinc plate on one side with the help of a clip. Place a graphite rod at the middle of the beaker and surround it with manganese dioxide (take filter paper and adhesive tape). First connect the graphite rod and the zinc plate to a voltmeter, then with the electric motor. 

Filter stick, sinter porosity 3 (or cannula, filter paper and PTFE tape). 

Source description Dried deposit ofbarium chloride on a filter-paper disk sealed between two layers of polyester tape that are supported on an aluonnuna annulus ... 

The droplet cell. Fig. 2(d), has uniform current distribution and shrunken dimensions that allow resistive electrolytes to be used [5]. This approach was developed for the use of pure water as an electrolyte as a means to mimic atmospheric corrosion, but it can be used with any electrolyte. An area of a flat sample is exposed through a hole in a piece of protective tape. Electroplater s tape is a very resistant tape with good adhesion that is useful for this and other masking applications in corrosion. If the hole in the tape is made with a round punch, the same punch can be used to make circular dots from pieces of filter paper. One such dot is placed securely into the exposed hole. A small (typically 10-20 gl) droplet of soluhon is placed on the filter paper using a calibrated pipette. This wet filter paper acts as the electrolyte. A piece of woven Pt mesh is placed on top of the wet filter paper, and a reference electrode is held against the back of the Pt counterelectrode. As mentioned, the small dimensions allow the use of even very pure water. This simulates atmospheric corrosion, in which a thin water layer forms on the surface. As in atmospheric corrosion, soluble species on the sample surface and pollutant gases in the air are dissolved into the water droplet, which provides some conductivity. This technique has been used... 

Denature the phage by placing the filters (plaque side up) on pads of Whatman 3MM paper saturated with the following solutions for 3 each (10) Solution 1— O.SA NaOH, l.SMNaCl Solution—2 1.0MTris-HCl,pH7.5, l.SMNaCl Solution 3—2X SSC. Next, transfer the filters to 3MM paper, and allow to air-dry. Interleave the filters between circles of filter paper, and secure the entire stack with tape. Bake at 80°C for 30 min. 

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