Paper liners

One milliliter each of the borneol solution and the oxidizing solution are mixed in a test tube and briefly shaken. A TLC slide is spotted with the borneol solution, the camphor solution, and the ether layer of the reaction mixture. Spotting is done by means of a capillary melting point tube used as a dropper and filled with a 5 mm sample. The slide is developed in a wide-mouth jar containing a filter paper liner and a few milliliters of chloroform (Fig. A3.20). After development (the solvent front rises to within 1 cm of the top), the slide is removed, the solvent is allowed to evaporate, and the slide is placed in a covered wide-mouth jar containing a few crystals of iodine. The spots readily become visible and the progress of the reaction can easily be followed. With periodic shaking, the oxidation is complete in about 30 minutes. 

As the paste separator is relatively thick compared with the paper liner, about 10% or more manganese dioxide can be accommodated in a paper-lined cell, resulting in a proportional increase in capacity. The pasted separator carbon—zinc cells were phased out more then a decade ago. All the cells made since then are paper-lined constructions. 

For the storing of textiles on new wooden shelving or drawers, a coating of a polyurethane varnish may be applied to seal the wood. Sufficient time, up to a month, should be allowed for the coating to dry. The shelves then can be lined with acid-free, buffered papers purchased from archival paper supply firms. These papers liners can be cut to fit the contour of any object and so need not to be noticeable in a display. 

It is important that saturated conditions are attained for running TLC plates. This is best accomplished by using small tanks with filter paper liners and sufficient solvent, and by leaving the tank to equilibrate for at least 30 minutes before running the plates. A well-fitting lid is essential. 

Preheat oven to 350°F and grease a 12-cup muffin tin with extra-virgin olive oil (or line with unbleached paper liners). 

Paper liners, linings and laminations containing paper... 

Preparative-scale plates are usually developed in rectangular glass tanks (e.g. 21 x 21 X 9 cm) lined with thick filter paper on all sides. The chamber is charged with sufficient mobile phase for the development step, and to soak the filter paper liner. Equilibration of the vapor phase typically requires 1 -2 h. Saturated developing chambers are preferred to minimize the formation of irregular solvent fronts and developed sample bands. The plates are usually inserted in a rack that holds them in a vertical position, and allows several plates to be developed simultaneously. Ascending development typically requires 1-2 h for a solvent-front migration distance of 18 cm. 

Prepare five micropipettes to spot the plate. The preparation of these pipettes is described and illustrated in Technique 20, Section 20.4. Prepare a TLC development chamber with methylene chloride (see Technique 20, Section 20.5). A beaker covered with aluminum foil or a wide-mouth, screw-cap bottle is a suitable container to use (see Technique 20, Figure 20.4). The backing on the TLC plates is thin, so if it touches the filter paper liner of the development chamber at any point, solvent will begin to diffuse onto the absorbent surface at that point. To avoid this, be sure that the filter paper liner does not go completely around the inside of the container. A space about 2.5 inches wide must be provided. Note This development chamber will also be used for Experiments 6C and 6D.)... 

Place the TLC plate in the development chamber, making sure that the plate does not come in contact with the filter paper liner. Remove the plate when the solvent front is 1-2 cm from the top of the plate. Using a lead pencil, mark the position of the solvent front. Set the plate on a piece of paper towel to dry. When the plate is dry, place the plate in a jar containing a few iodine crystals, (see Technique 20, Section 20.7) cap the jar, and leave it in the jar until the spots begin to appear. Remove the plate from the jar and lightly outline all the spots that became visible with the iodine treatment. Using a ruler marked in millimeters, measure the distance that each spot has traveled relative to the solvent front. Calculate the values for each spot (see Technique 20, Section 20.9). Explain the relative positions of the three compounds in terms of their polarities. Identify the compound or compounds that are found in the unknown mixture. At the instructor s option, submit the TLC plate with your report. 

Place the TLC plate in the development chamber, making sure that the plate does not come in contact with the filter paper liner. Remove the plate when the solvent front is 1-2 cm from the top of the plate. Using a lead pencil, mark the position of the solvent front. As soon as the plates have dried, outline the spots with a pencil and indicate the colors. This is important to do soon after the plates have dried because some of the pigments will change color when exposed to the air. 

Filter paper liner in jar (should be completely moistened by solvent)... 

A coating of silica aerogel, in a silicone oiL dispersed in water with an organ osilane triol, on the paper liner of a baking pan prevents adhesion of baked goods (585). 

CHAMBER. The tank, jar, or vessel of other type in which thin-layer chromatographic development is carried out. A normal chamber is a closed, glass vessel used for linear, ascending one- or two-dimensional development with (saturated) or without (unsaturated) mobile-phase-soaked filter paper liner. 

N-CHAMBER. A square or rectangular tank or chamber, or a cylinder, with (saturated) or without (unsaturated) a paper liner and covered with a top, for development of TLC or HPTLC plates. 

Industrial Heavy Duty. Application Intermittent medium- to heavy-rate discharges, low to moderate cost. The industrial heavy-duty zinc-carbon battery generally has been converted to the zinc chloride system. However, some types continue to include ammonium chloride and zinc chloride (ZnCl2) as the electrolyte and synthetic electrolytic or chemical manganese dioxide (HMD or CMD) alone or in combination with natural ore as the cathode. Its separator may be of starch paste but it is typically a paste-coated paper liner type. This grade is suitable for heavy intermittent service, industrial applications, or medium-rate continuous discharge. 

FIGURE 8.2 Typical cutaway view of cylindrical Leclanche battery ( Eveready ) paper liner separator, asphalt seal. 

Crates were used for packing a few comparatively bulky CWS items, such as smoke tanks and smoke generators. These had to be specially designed in each case, with particular care to make sure that hard surfaced points on the item or the bracing were not so placed as to abrade the waterproof paper liner. Corrosion prevention for hardware was accomplished by cleaning all ferrous surfaces and coating them with grease or oil. 

The chemical methylnaphthalene was detected in the wax paper liners of certain Kellogg s -brand breakfast cereals in 2010. 

Media reports differ on whether the chemical identified was methyinaphthalene (Harrington 2010) or 2-methylnaphthalene (Layton 2010). It appears that some form of methyinaphthalene was used in the wax paper liners (see Fig. 10.1 for chemical structures of 1- and 2-methylnaphthalene), Kellogg identified suspect samples of the wax paper liner, reserved tested samples, and then destroyed the remaining inventory of the wax paper to keep it out of future production (Harrington 2010). Kellogg does not use either 1-methylnaphthalene or 2-methylnaphthalene for the manufacture of cereal box liners in Europe (Harrington 2010). The levels of 1- or 2-methylnaphthalene found in the tainted cereals in the U.S. have not been made public by either the FDA or the Kellogg Company. 

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