Carboxylic acid analyser

The analyses of aromatic components were performed on a 1525 Binary Waters HPLC with a dual absorbance detector using a Symmetry Cl 8 column and a mobile phase of methanol and water. Carboxylic acids analyses were performed using the same HPLC system with an Atlantis dC18 column and mobile phase. pH was monitored with a Coming 430 pH meter. For most experiments, the total organic carbon was also analyzed using a Shimadzu 5050 TOC analyzer equipped with a NDIR detector coupled with an autosampler ASI 5000. 

Nakajima, M., Ozawa, Y., Tanimura, T. and Tamura, Z. (1976), A highly efficient carboxylic acid analyser and its application. J. Chromatogr. y 123,129. 

The silver salts of most carboxylic acids are only sparingly soluble in cold water, and hence are readily prepared. Moreover they very rarely contain water of crystallisation, and therefore when dried can be analysed without further treatment. The analysis itself is simple, rapid and accurate, because gentle ignition of a weighed quantity of the silver salt in a crucible drives off the organic matter, leaving a residue of pure metallic silver. 

Amides are derivatives of carboxylic acids, so that their coordination behavior to boranes might be similar to that of their parent compounds. B-NMR spectroscopic studies have shown that compounds 31 and 32 are monomeric species in solution, while compounds 33 and 34 with the more Lewis acidic 9-borabicyclo[3.3.1]nonyl unit form aggregates that may be dimeric, oligomeric, or polymeric. The grade of association could not be determined by mass spectrometric analyses, because in all cases only the monomer is liberated into the gas phase [65]. 

For the final optimization, a modified factorial design involving three concentration levels of triethylamine and three pH levels was used. From these results, it was clear that the optimum conditions for the analysis of the carboxylic acid were so different from those required for the other compounds studied that it was not sensible to attempt to analyse all fonr together and indeed that carboxylic acids were better analysed by using conventional reversed-phase HPLC than by using ion-pairing. 

Resting cells of A. nicotianae FI1612 also catalyzed the carboxylafion of 2-methylindole and quinoxaline. The activities toward 2-methylindole and quinoxaline were 37 and < 1% of the activity toward indole, respectively. The reaction products of the reverse carboxylafion, indole-3-carboxylic acid and 2-methylindole-3-carboxylic acid, were isolated and identified through physicochemical analyses with the authentic compounds as reference. 

In addition to the natural waxes, a number of synthetic waxes were analysed with GALDI-MS carboxylic acids (Hoechst wax-L, -S), esters (Hoechst wax-FL, -H, -O), and glycol esters (Hoechst wax-KP, -KPS). In most cases, significant mass spectra were obtained. The mass spectrum of polyethylene glycol (Carbowax 6000) showed a series of signals the spacing of m/z 44 between the signals corresponds to one oxyethylene unit. 

Infra-red, microwave, and X-ray photoelectron spectroscopy Infra-red and ultra-violet spectroscopy has been widely used for investigating the structure of intermolecularly hydrogen-bonded complexes in the solid state (Novak, 1974) and in solution (Zundel, 1976, 1978 Clements et al., 1971a,b,c Pawlak et al., 1984). By analysing the infra-red spectra of equimolar liquid mixtures of amines with formic or acetic acid, the relative importance of structures [10] and [11] was estimated (Lindemann and Zundel, 1977). It was proposed that [10] and [11] make equal contributions to the observed structure of the complex when the p -value of the carboxylic acid is approximately two units lower than that of the protonated amine. 

By reacting first with ethyl bromoacetate, a fluorinated carboxylic acid (III) resulted, which was then converted into the acid chloride (IV) and subsequently reacted with hydroxyethyl methacrylate or hydroxypropyl methacrylate giving rise to the monomers V, as shown in Figure 1.2. All these monomers are clear, colorless liquids, and were characterized by NMR and FTIR spectra and elemental analyses. 

These desiratives have been useful for gas chromatographic and mass spectral analyses, but since they are very sensitive to hydrolysis, their use as protecting group in multistep organic synthesis become limited. But since trimethylsilyl ethyl derivatives are more stable towards hydrolysis and can be easily removed under very mild conditions, they are more useful for protection of amines and carboxylic acids. 

No carboxylic acid functionality was detected either by thin-layer chromatographic analyses or by end-group titration. Therefore, procedures are now available to control the carbonation of polymeric organolithium compounds to efficiently produce either the carbox-ylated chain ends or the corresponding ketone dimer. 

Detailed analyses of partially fluorinated compounds from the ECF of amines, and relatively simple sulphonic acid derivatives have been performed with interesting and illuminating results but do these observations translate into other complex systems, e. g., long chain carboxylic acid derivatives The experiments have yet to be done. 

In Chapter 2 the DSC technique is discussed in terms of instruments, experimental methods, and ways of analysing the kinetic data. Chapter 3 provides a brief summary of epoxy resin curing reactions. Results of studies on the application of DSC to the cure of epoxy resins are reviewed and discussed in Chapter 4. These results are concerned with the use of carboxylic acid anhydrides, primary and secondary amines, dicyanodiamide, and imidazoles as curing agents. 

A reversed-phase liquid chromatographic method was developed for simultaneous determination of carboxylic acids, phenolic compounds, and SA in white wines (84). The diluted samples are injected into a Spherisorb ODS-2 column with a gradient of sulphuric acid (pH 2.5)/methanol as mobile phase. A diode array detector is used, set at 210 nm for carboxylic acids and altered to 278 nm, during the run, for phenolics and SA. The identification of compounds is based on retention time and UV spectra. Some cleanup methods (Sep-Pak C18 and an ion-exchange column) were tested and did not improve the results. The analysis was considered simple, with no sample preparation. Application of this method was illustrated by analyses of Brazilian Welchriesling wines (84). 

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