Tic plates

Sulfony1oxaz1ridines, preparation, 66, 207, 208 Sulfosalicylic acid spray for tic plates, 66, 216 Sulfur chloride, 65, 159... 

The channel is a square-shaped tube fabricated from Zircaloy 4. The outer dimensions arc 5,518 inches (14 centimeters) by 5,518 inches (14 centimeters) by 166,9 inches (424 centimeters) long, The reusable channel makes a sliding seal lit on the lower tie plate surface. It is attached to the upper tic plate by the channel fastener assembly, consisting of a spring and a guide, and a cap screw secured by a lock washer. The fuel channels direct the core coolant flow through each fuel bundle and also serve to guide the control rods. 

Tic is by far the most widely used technique for rapid, routine reaction monitoring and it is essential that the lab should have permanent facilities for visualization of tic plates. A range of solvent dips, a heat gun, an iodine tank and a small uv lamp are usually all that is necessary (see Chapter 9). 

There are two main types of coating for tic plates silica and alumina. Silica plates are most commonly used, they are slightly acidic and are suitable for running a broad range of compounds. Most of the information in this section refers directly to silica plates, but the same principles apply when using alumina plates. Alumina plates are slightly basic and are commonly used when a basic compound will not run very well on silica. 

Cut a tic plate which is 5cm long, and wide enough so that about 0.5cm can be left between each spot (obviously the width of the plate is dependent upon the number of spots to be run on it). 

The absolute distance which a compound rans up a tic plate is extremely variable, depending on the exact conditions under which the plate was run. It is therefore much more informative to run comparative tics. When analyzing a reaction mixture, it should always be run in comparison with the starting material and a mixed spot should also be run. This is very important because it often enables you to distinguish between compounds which run in almost identical positions. 

Place the plate upright in a tank lined with a filter paper and containing the chosen solvent system (to a depth of ca. 0.3cm as shown in Fig. 9.15b). Allow the solvent to creep up the tic plate until it is ca. 0.3cm from the top, then remove it, and mark the level of the solvent front (Fig. 9.15c). A 150ml lipless beaker makes a convenient tic tank and a petri dish can be used as a cover. 

The three general ways to visualize spots on tic plates are listed below. Any one or combination of these techniques can be used, but they should be carried out in the order shown, as the first two techniques are nondestructive. 

The relative distance which a compound travels up a tic plate depends on two factors, its polarity and that of the solvent. In the same solvent, the more polar the compound, the more tightly it is bound to the silica (or alumina) and the less it travels. There are some common trends, and with experience, it is often possible to predict whether a product will be less or more polar than the starting material. For example when a ketone, or ester is reduced, the resultant alcohol is almost always significantly more polar, and a clean transformation to a lower running spot will indicate a successful reaction. If the polarity of the solvent used for elution is increased the spots... 

Acidic and basic compounds often streak up the tic plate. However, they will usually form distinct spots if, for acids a small amount of a carboxylic acid (e.g. acetic acid) is added to the solvent system, and for bases a small amount of amine (e.g. triethylamine) is added. 

The silica on tic plates is acidic in nature, and so compounds that are sensitive to acid may well decompose on tic. There are several ways of getting around this problem, you can use alumina tic plates (these suffer from the disadvantage that resolution is generally not as good, and the plates are basic in nature), or alternatively you can add a small amount of an amine (usually ammonia or triethylamine) to the solvent mixture to neutralize the acidic sites on the silica. 

For analysis of the column fractions, have a tic tank close at hand containing an appropriate solvent, and several tic plates, cut to about 4cm wide. 

Great skill is required to run preparative tics effectively, and even then sample obtained is often contaminated with significant quantities of sase and tic plate binding agent. Since there are now much better modem all scale separation techniques available, we do not recommend Treparative tic (see below foT details of preparative hplc and Chapter 12 for re on small scale flash chromatography). 

A TIC plate (20 X 20 cm) has to be sprayed with a minimum of 10 ml SbCI, reagent and heated at I00°C for about 8-10min evaluation is done in vis and UV-355nm (see Table 1), Changes are observed in the fluorescence response if the sprayed plate is allowed to stand for a longer time. In visible light, the zones appear mainly grey, violet or brown. 

About 10 g solid iodine are spread on the bottom of a chromatograph tank the developed TIC plate is placed into the tank and exposed to iodine vapour. 

Standard tubes are available for applying accurate volumes (1-10 il) of sample solutions to chromatographic paper and tic plates. Alternatively, a... 

The partially purified anacardic acids, from both the resistant and susceptible plants were further cleaned up prior to hpic separation using Merck 20x20cm, 2mm thickness preparative tic plates. The compounds were applied to several plates as the dimethylated compounds (diazomethane, 30 minute treatment (fi.)), and run in the same two step solvent system described above. The plates were viewed at 254nm and the anacardic acid bands were cut and eluted from the silica using methylene chloride (3x30mL). The purified anacardic acids were then ready for separation by preparative hpIc. 

Preliminary identification of many lipids may be obtained by the use of specific sprays on tic plates. Reagents such as 2, 7 -dichlorofluorescein and rhodamine 6G permit the nondestructive revelation of lipid bands and, if sufficient lipid is present, a water spray can also be used. Exposure to iodine vapor can be employed provided fatty acid analysis is not required. More specific chemicals include ninhydrin, Schiff-periodate, and Zinzadze s reagent (cf. Kates, 1972 Stahl, 1969). 

General quantitization of separated lipids can be obtained by gravimetric analysis of the eluted compounds. Densitometric analysis of carbonized areas can be utilized for tic plates (cf. Hitchcock and Nichols, 1971) or, more accurately, from silica rods (Vandamme et al., 1978). 

The most accuracy is obtained when the elution of lipids from tic plates is unnecessary. Glycoglycerolipids can be measured with phenol-H2S04 (Roughan and Batt, 1968, 1969) and phospholipids by organic phosphorus analysis (Rouser et al., 1969). Acyl lipids are also conveniently quantitated from their fatty acid content (see Section VI,C,2), but care should be taken that the transmethylation method used is quantitative for all the lipid classes analyzed. 

Transfer any excess of the eluting solvents to a container for nonhalogenated organic liquids. Dispose of the used TIC plates in a container for nonhazard ous materials. 

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