Discussion of Procedures

Lundquist and Kirk (1971) treated spruce lignin with the acidolysis reagent at reflux temperature for 4, 8, and 24 h Ketol la (Fig 6 11) predominates in the 4-h acidolysis mixture (yield, 4 6% of the lignin) and prolonged treatment does not result in any appreciable increase in the yield of acidolysis monomers The yields of the primary ketols la and 2a (Fig 6 11) from birch lignin (a typical 

A variety of work-up procedures have been described in the literature. Lundquist and Kirk (1971) applied gel permeation chromatography to separate the acidolysis monomers from polymeric materials in the initial step. This is, however, not a requirement when the acidolysis monomers are analyzed by gas chromatography as their trimethylsilyl derivatives. 

The rate of derivatization of different compounds varies when trimethylsilyl derivatives are prepared (Lundquist and Kirk 1971). Another complication arises from the fact that enolization and subsequent formation of enol derivatives occur during the derivatization treatment (Lundquist and Kirk 1971). Ketol la (Fig. 6.1.1), for example, has been shown to give rise to three different derivatives (Fig. 6.1.3) (Lapierre et al. 1983a). One approach for overcoming these difficulties consists of derivatization under mild conditions in combination with a gas chromatographic study of the rate of derivatization (Lundquist and Kirk 1971, Pometto and Crawford 1985). A second solution to this problem consists of performing the silylation under conditions that secure complete derivatization and analysis of all types of derivatives formed (Lapierre et al. 1983a). The latter principle has been adopted in the preferred acidolysis procedure. 

In an attempt to circumvent the analytical problems discussed above, a method for the analysis of acidolysis monomers has been developed which involves reduction of carbonyl and carboxyl groups with borane dimethyl sulfide 

J Separation was performed with a normal phase column (Radial-PAK Si) using hexane-ethyl acetate (3 1 v/v) as eluent Elution volumes are listed relative to that of the triacetate of 6c (elution volume = 20 ml), the void volume of the system was 3 6 ml 

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Extensive discussions of procedures for energizing molecules are given elsewhere [5],... 

General schemes for the identification of natural and synthetic fibers have been estabhshed by the Textile Institute and by the American Association of Textile Chemists and Colorists (8). A comprehensive treatment of burning, solvent, staining, microscopy, and density techniques has been given (9) and a general discussion of procedures for identifyiag synthetic fibers has been presented (10). 

This section starts with analysis of the results of one particular experiment in order to detail properly the process gone through for each. There follows a validation of the RDC mathematics (an extension of that done by the originators of the method [16]). Results for the o— /o/w programme are then summarised, including some unusual effects that have been observed. In this section, discussions of procedure and rationale will be made, in order to concentrate on deeper issues in Section 6.5. 

The FDA regulations end with a discussion of procedures for Disqualification of Test Facilities (subpart K). 

Section 14.2 provides a thorough discussion of procedures for writing the empirical law of mass action for gas-phase, solution, and heterogeneous reactions, with specific examples for each. 

The wide variety of possible choices of separation processes bas been catalogued by King. Also, a detailed discussion of procedures for selecting a separation process is provided by Null in Chepter 22. Hare, some comments on separation process selection are included to provide some perspective for later discussion. 

See Chapter 12, Significant New Use Rules for a discussion of procedures for the issuance of SNURs. 

Another statistic often calculated is an overall index of acceptability of the form (T- Q/(r + C), where T and C are defined as above. This statistic has an expected value of 0 when there is no difference in preference of the test and control treatments and a range from - 1 (when the test treatment is never chosen) to + 1 where the test treatment is completely preferred over the control. While this statistic allows the expression of the relative attraction and deterrence of a range of compounds, its statistical properties are not well understood. The statistic is not normally distributed, and the occurrence of negative values precludes the use of common transformations (e.g., log, arcsine, square root) to remove some deviations from normality. Thus, if this statistic is used, it should be analyzed only by nonparametric, distribution-free statistical tests based on ranks. Further discussion of procedures and criteria for selecting statistical tests can be found in many standard texts and manuals for a number of statistic analysis packages for use with computers (e.g.. Steel Torrie 1980 SAS Institute 1989 Sokal Rohlf 1995). 

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