Trace organic analysis, principles

As described above, individual packaging components will invariably contain complex mixtures of chemical entities (e.g., additives and oligomers), many if not most of which are at relatively trace levels (i.e., pg/g and lower). The principles of Trace Organic Analysis, as developed in the environmental, geochemical, and bioanalytical fields, can be applied to the problem of identification and quantification of these individual chemical entities, whether as extractables or as leachables.f The general process is as follows ... 

Typical areas of application are identification of trace (ppm or ppb level) volatile organics in complex mixtures (e.g. olfactory principles) and monitoring of residual monomers in polymeric materials. Apart from HS-GC, analysis of volatiles can also be carried out by a variety of other methods, including hydrodistillation, SFE, US, adsorption trapping and SPME. 

Principles and Characteristics Combustion analysis is used primarily to determine C, H, N, O, S, P, and halogens in a variety of organic and inorganic materials (gas, liquid or solid) at trace to per cent level, e.g. for the determination of organic-bound halogens in epoxy moulding resins, halogenated hydrocarbons, brominated resins, phosphorous in flame-retardant materials, etc. Sample quantities are dependent upon the concentration level of the analyte. A precise assay can usually be obtained with a few mg of material. Combustions are performed under controlled conditions, usually in the presence of catalysts. Oxidative combustions are most common. The element of interest is converted into a reaction product, which is then determined by techniques such as GC, IC, ion-selective electrode, titrime-try, or colorimetric measurement. Various combustion techniques are commonly used. 

As discussed in Chapter 9.C, ambient particulate matter contains inorganic elements and ions, including trace metals, as well as graphitic (elemental) carbon and a wide variety of organic compounds and water. Techniques in common use to measure these species are discussed very briefly here. For further details of the principles behind these techniques, the reader should consult instrumental analysis texts (e.g., Skoog et al., 1998). Specific applications of various methods to particles in the atmosphere are described in the book edited by Spurny (1986) as well as the references at the end of this chapter. 

Our focus will be on CZE in this book although MEKC holds great potential for selective organic priority pollutant trace analysis. After we introduce the underlying principles of CZE, we will cite this author s efforts in developing a method to separate inorganic anions. 

This simple principle is still apphed in trace analysis, often in miniaturized form, as either an extraction procedure per ie or as a clean-up method (or both). Classical LLE uses large amounts of organic solvent (an environmental concern) and is slow, while the various miniaturized methods use much smaUer amounts of solvent, are much faster and more amenable to automation, and... 

In adsorptive stripping voltammetry (AdSV) metal chelates and organic molecules are accumulated by adsorption at the surface of the working electrode. If these compounds are electrochemically active, i.e., if they are reducible or oxidizable. their subsequent voltammetric determination is possible. By this principle of so-called adsorptive stripping voltammetry, organic and organomet-allic compounds are determined in the ultra-trace range. This technique is particularly important for the trace analysis of metals that are not readily deposited as the element on mercury electrodes... 

Polarography is an excellent method for trace and ultra-trace analysis of inorganic and organic substances and compounds. The basic process of electron transfer at an electrode is a fundamental electrochemical principle, so polarography can be used... 

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