RIPS

VIII. An Analytical Derivation for the Possible Sign Rips in a Three-State System... 

To examine a sample by inductively coupled plasma mass spectrometry (ICP/MS) or inductively coupled plasma atomic-emission spectroscopy (ICP/AES) the sample must be transported into the flame of a plasma torch. Once in the flame, sample molecules are literally ripped apart to form ions of their constituent elements. These fragmentation and ionization processes are described in Chapters 6 and 14. To introduce samples into the center of the (plasma) flame, they must be transported there as gases, as finely dispersed droplets of a solution, or as fine particulate matter. The various methods of sample introduction are described here in three parts — A, B, and C Chapters 15, 16, and 17 — to cover gases, solutions (liquids), and solids. Some types of sample inlets are multipurpose and can be used with gases and liquids or with liquids and solids, but others have been designed specifically for only one kind of analysis. However, the principles governing the operation of inlet systems fall into a small number of categories. This chapter discusses specifically substances that are normally liquids at ambient temperatures. This sort of inlet is the commonest in analytical work. 

Another variant (the cone spray) allows the sample solution to flow down the sides of an inverted cone and through a hole at the bottom of which flows a fast stream of argon gas. As the liquid film meets the gas, it is ripped apart into a finely dispersed aerosol (Figure 19.15). 

Uranium ores are leached with dilute sulfuric acid or an alkaline carbonate [3812-32-6] solution. Hexavalent uranium forms anionic complexes, such as uranyl sulfate [56959-61-6], U02(S0 3, which are more selectively adsorbed by strong base anion exchangers than are other anions in the leach Hquors. Sulfate complexes are eluted with an acidified NaCl or ammonium nitrate [6484-52-2], NH NO, solution. Carbonate complexes are eluted with a neutral brine solution. Uranium is precipitated from the eluent and shipped to other locations for enrichment. Columnar recovery systems were popular in South Africa and Canada. Continuous resin-in-pulp (RIP) systems gained popularity in the United States since they eliminated a difficult and cosdy ore particle/leach hquor separation step. 

The bearing housings and supports required extensive repair. All of the housing bores were pounded out, partieularly the bearing bores, whieh were pounded out up to one-quarter ineh. Ninety pereent of the threaded fasteners had been ripped out of their respeetive threaded holes and the dowel holes were all oval. The sealing steam ehamber of tlie bearing support was ripped away from the main support struemre. 

Energy surfaces of this type appear to have been described first by Hughes et al. in 1936. Their current popularity and utility are a consequence of developments by Albery, More O Ferrall, and Jencks, and they are sometimes called More O Ferrall plots or More O Ferrall-Jencks plots. We will refer to them as RIP diagrams, this designation arising from the symbolism in Fig. 5-19. 

To make this more specific. Table 5-3 gives examples of several reaction types that fit the RIP pattern. Consider nucleophilic substitution on saturated carbon. The concerted mechanism is the one-step bimolecular 5, 2 process ... 

We will return to our consideration of RIP diagrams. Figure 5-22 summarizes the possible reaction paths. Recall that an intermediate is a state of minimum energy on the reaction path, so that all four comers may constitute energy minima, but for any given type of reaction it is unlikely that both I and 1 will be of comparable stability. As Table 5-3 indicates, one of these is apt to be the favored intermediate. 

The essential goal is to locate the transition state on the RIP diagram. This involves speeifying two eoordinates, so two quantitative progress variables are required. One approaeh, fairly widely applied, ean be illustrated with the study by Hill et al. of the general aeid-eatalyzed addition of substituted anilines to diey-anamide. The overall reaetion is... 

Figure 5-23. RIP diagram for the general acid-catalyzed addition of anilines to dicyanamide.

The R— P reaction is called the main reaction, and the hypothetical process I P is called the disparity reaction. Figure 5-24 is an RIP diagram with two coordinate systems. In the type of diagram we have used thus far, the coordinates are u and v for example in Fig. 5-23, u = and v = aHA- The normalized... 

Figure 5-24. The u.v and x,y coordinate systems of Grunwald s analysis of the RIP diagram. The u.v coordinates are in parentheses and the jr,y coordinates are in brackets.

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