Analysis of organic compounds

In gas-solid extractions the sample is passed through a container packed with a solid adsorbent. One example of the application of gas-solid extraction is in the analysis of organic compounds for carbon and hydrogen. The sample is combusted in a flowing stream of O2, and the gaseous combustion products are passed through a series of solid-phase adsorbents that remove the CO2 and 1T20. 

Controlled-potential coulometry also can be applied to the quantitative analysis of organic compounds, although the number of applications is significantly less than that for inorganic analytes. One example is the six-electron reduction of a nitro group, -NO2, to a primary amine, -NH2, at a mercury electrode. Solutions of picric acid, for instance, can be analyzed by reducing to triaminophenol. 

We inferred that these properties might be exploited in a series of unique derivatizing reagents designed specifically for trace analysis of organic compounds using HPLC separation and fluorescence detection. The use of these pyridones for the analytical purposes reported here is based on their acidic properties. Treatment of a lH-2-pyridone with a base converts the pyridone to its salt. 

Jacob J, Belliardo JJ, Karcher W, Lindsey AS, and Wagstafee PJ (1994) Reference materials for the analysis of organic compounds of environmental and occupational concern. Separation and Purification Methods 23 17-49. 

Law RJ, de Boer ) (1995) Quality assurance of analysis of organic compounds in marine matrices application to analysis of chlorobiphenyls and polycyclic aromatic hydrocarbons. In Quevau-... 

Thermospray (TSP) is another soft ionisation technique which produces predominantly MH+ or (M — H) ions, together with some fragmentation. TSP is best suited to the analysis of organic compounds of low molecular mass (<1000 Da) that exhibit some polarity. Polymer additive molecules fall in this wide category. 

Whereas SPE is a sample cleanup method, SPME is essentially a solvent-free sampling method. Stir bars in hyphenated SBSE-TDS-CGC configuration for product control analysis are a powerful tool for the extraction and analysis of organic compounds in aqueous matrices. 

Z. Zhang, J. Pawliszyn, Analysis of organic compounds in environmental samples using headspace solid phase microextraction, J. High Resol. Chromatogr., 16, 689 692 (1993). 

These methods may prove useful in the qualitative analysis of organic compounds, once the selectivities of the precipitants are understood. The metallic oxides suffer from the disadvantage of producing a precipitate which is difficult to filter, while calcite and zirconium phosphates produce relatively well-mannered precipitates. Even when the efficiencies of collection of various model compounds in seawater is known, the immense variety of organic compounds in seawater will keep this technique largely qualitative. 

Wangersky PJ, Zika RG (1978) The analysis of organic compounds in seawater. Report 3, NRCC 16566, Marine Analytical Chemistry Standards Program... 

Each of the major techniques of molecular spectrometry, including mass spectrometry, will now be examined in more detail. Exercises in the interpretation of spectral data in relation to the identification and structural analysis of organic compounds are given at the end of the chapter. 

PMR spectrometry is an extremely useful technique for the identification and structural analysis of organic compounds in solution, especially when used in conjunction with infrared, ultraviolet, visible and mass spectrometry. Interpretation of PMR spectra is accomplished by comparison with reference spectra and reference to chemical shift tables. In contrast to infrared spectra, it is usually possible to identify all the peaks in a PMR spectrum, although the complete identification of an unknown compound is often not possible without other data. Some examples of PMR spectra are discussed below. 

Identification and structural analysis of organic compounds. Determination of trace impurities in a wide range of inorganic materials (spark source mass spectrometry). 

Used in conjunction with infrared, NMR, UV and visible spectral data, mass spectrometry is an extremely valuable aid in the identification and structural analysis of organic compounds, and, independently, as a method of determining relative molecular mass (RMM). The analysis of mixtures can be accomplished by coupling the technique to GC (p. 114). This was formerly done by using sets of simultaneous equations and matrix calculations based on mass spectra of the pure components. It is well suited to gas... 

M. Pesez and J. Bartos in "Colorimetric and Fluori-metric Analysis of Organic Compounds and Drugs," Marcel Dekker, New York, 1974. 

This chapter presents an overview of the various methods for collecting and preparing samples for analysis, from classical to more modern techniques. We provide below a general overview, outlining some of the theory and practice of each technique. Our focus is mainly on the analysis of organic compounds of interest (analytes) in a variety of matrices, such as environment, food, and pharmaceuticals. For further reading, the analysts are referred to a more detailed discussion of these techniques in various textbooks and key references [3-7]. 

Infrared spectra differ markedly from the typical ultraviolet or visible spectrum. Infrared spectra are marked by many relatively sharp peaks and the spectra for different compounds are quite different. This makes infrared spectroscopy ideal for qualitative analysis of organic compounds. 

J.H. Beynon, Qualitative analysis of organic compounds by mass spectrometry, Nature, 174 (1954) 735-737. 

Analysis of organic compounds. Large number of organic molecules absorb radiation in ultraviolet and visible region. So molecules having high molecular absorptivities can be determined directly. 

Several years later, the next step in the application of MS-MS for mixture analysis was developed by Hunt et al. [3-5] who described a master scheme for the direct analysis of organic compounds in environmental samples using soft chemical ionisation (Cl) to perform product, parent and neutral loss MS-MS experiments for identification [6,7]. The breakthrough in LC-MS was the development of soft ionisation techniques, e.g. desorption ionisation (continuous flow-fast atom bombardment (CF-FAB), secondary ion mass spectrometry (SIMS) or laser desorption (LD)), and nebulisation ionisation techniques such as thermospray ionisation (TSI), and atmospheric pressure ionisation (API) techniques such as atmospheric pressure chemical ionisation (APCI), and electrospray ionisation (ESI). 

For quantitative analysis of organic compounds in general by means of liquid chromatography-electrospray ionisation mass spectrometry (LC-ESI-MS), one should be aware of two major factors, which may strongly impact on the outcomes. These are directly associated with the process of ion generation in the interface. 

Arthur CL, Pratt K, Motlach S, et al. 1992. Environmental analysis of organic compounds in water using solid-phase microextraction. J High Resolut Chromatogr 15(11) 741 -744. 

The size of the atoms and the rigidity of the bonds, bond angles, torsions, etc. are determined empirically, that is, they are chosen to reproduce experimental data. Electrons are not part of the MM description, and as a result, several key chemical phenomena cannot be reproduced by this method. Nevertheless, MM methods are orders of magnitude cheaper from a computational point of view than quantum mechanical (QM) methods, and because of this, they have found a preferential position in a number of areas of computational chemistry, like conformational analysis of organic compounds or molecular dynamics. 

Beynon, J.H. Qualitative Analysis of Organic Compounds by Mass Spectrometry. Nature 1954,174. 735-737. 

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