Plate drying process

After curing, the plates are allowed to finish the drying process in ambient or elevated temperature air. The moisture and metallic lead content of the cured plates should be substantially reduced to less than 2%. 

Comparison Data—Plate Dryers Comparative studies have been done on products under both atmospheric and vacuum drying conditions. See Fig. 12-79. These curves demonstrate (1) the improvement in drying achieved with elevated temperature and (2) the impact to the drying process obtained with vacuum operation. Note that cui ve 4 at 90°C, pressure at 6.7 kPa absolute, is comparable to the atmospheric cui ve at 150°C. Also, the comparative atmospheric cui ve at 90°C requires 90 percent more diying time than the vacuum condition. The dramatic improvement with the use of vacuum is important to note for heat-sensitive materials. 

In fact, it is extremely important to eliminate as completely as possible the solvent imbedded into the thin layer of coated adsorbent. It is achieved conveniently first by air-drying the TLC plates for a duration of 30 minutes and then in a hot-air oven maintained at 110 °C for another 30 minutes and subsequently cooling them in a dessicator. This drying process helps a great extent in rendering the adsorbent layer active. In order to achieve very active layers, silica gel and alumina coated plates may be heated upto 150 °C for a duration of 4 hours and colling them in a dessicator. 

Blotting membranes and TCL plates are processed analogously. Incubate the dry plate or membrane in Soln. B for 5-10 min, dry again, and expose to film. 

Repeat this experiment with the latex cooled in ice and the plate at ice temperature. Allow the drying process to take place near the ice temperature. Again note the properties. 

SLI batteries are also supplied in a dry charged state and are activated simply by filling with electrolyte. Plates for such batteries have extra additives, such as antioxidants in the negative active mass, and forming is followed by one of a number of controlled drying processes. 

The nature of the charge in a desiccator, which is placed in the lower compartment below the metal gauze plate, is dependent on whether water or organic solvents are to be removed and whether acidic or basic vapours are likely to be evolved during the drying process. Suitable charges are discussed in Section 2.20. 

The procedure should be amenable to automation. For example, instead of using test tubes and centrifugation, the processes of filtration by a 96-well microplate into a 96-well collection plate, drying, reconstitution and injection onto the LC-MS/MS are more conducive to automation. 

Hot plates are also used to heat one type of material so that a second may be heated. These secondary heaters may include water baths, oil baths, sand traps, or aluminum plates. Water and oil baths are typically used to heat a drying flask on vacuum evaporators. Oil baths are more messy and require special clean up, but the oil (typically a silicone oil) will not evaporate during drying processes that can take up to several hours. Stronski came up with a very simple and easy solution to limit water evaporation. Stronski8 recommended that the user float Styrofoam popcorn or chips up to three inches deep on water. This suggestion not only limited evaporation, but extended the maximum controlled temperature range. 

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