Organic compounds, trace determination

Materials from a solvent-refined coal pilot plant and two simulated in situ oil shale retort facilities have been characterized for trace inorganic and organic compounds. The techniques used allowed the determination of some 30 elements, the chemical and physical forms of arsenic and mercury, and a large number of organic compounds. Satisfactory balances were obtained for most trace elements except mercury in effluents from the solvent-refined coal plant and one of the oil shale retorts. Approximately 60 organic compounds were determined quantitatively in process streams from the solvent-refined coal plant, and 20 organic compounds were determined in the crude shale oil from an oil shale retort pilot plant. 

Solvent extraction followed by gas chromatographic analysis is used to determine paraffin wax antioxidants (qv), ie, butylated hydroxyanisole and butylated hydroxytoluene and other volatile materials. Trace amounts of chlorinated organic compounds, eg, polychlorinated biphenyls, can be deterrnined by using a gas chromatograph with an electron-capture detector (22). 

The determination of organic compounds by their direct catalytic effect on indicator reaction rates is a relatively unexplored ai ea promising valuable analytical chai acteristics, as we have recently shown in the determination of traces of unsymmetrical dimethylhydrazine (UDMH) by the oxidation of 3,3, 5,5 -tetramethylbenzidine (TMB) by atmospheric oxygen initiated with persulfate [1]. 

The method of Carius for the determination of chlorine in organic compounds is, of course, absolutely quantitative, but is very tedious, and is scarcely suitable for the detection of very small traces of chlorine, as the weight of oil taken in a Carius determination never exceeds 0 5 grams. 

The high-purity water thus produced typically has a conductance of about 0.5 x 10-6fi-1cm-1 (0.5juScm-1) and is suitable for use under the most stringent requirements. It will meet the purity required for trace-element determinations and for operations such as ion chromatography. It must however be borne in mind that such water can readily become contaminated from the vessels in which it is stored, and also by exposure to the atmosphere. For the determination of organic compounds the water should be stored in containers made of resistant glass (e.g. Pyrex), or ideally of fused silica, whereas for inorganic determinations the water is best stored in containers made from polythene or from polypropylene. 

Chian et al. [69] point out that the Bellar and Iichtenberg [65] procedure of gas stripping followed by adsorption onto a suitable medium and subsequent thermal desorption onto a gas chromatograph-mass spectrometer is not very successful for trace determinations of volatile polar organic compounds such as the low molecular weight alcohols, ketones, and aldehydes. To achieve their required sensitivity of parts per billion, Chian et al. [69] carried out a simple distillation of several hundred ml of sample to produce a few ml of distillate. This achieved a concentration factor of between 10 and 100. The headspace gas injection-gas chromatographic method was then applied to the concentrate obtained by distillation. 

Quantitative and qualitative determination of metals and organic compounds at trace levels (10 4 to 10 8 M) relative precision 2-3%. Amperometric titrations are more versatile and more precise than polarography. 

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

A most important technique which has been developed as an extension of the isotope dilution principle is that of radioimmunoassay (RIA). Analyses by this method employ substoichiometric amounts of specific binding immuno-chemical reagents for the determination of a wide range of materials (immunogens) which can be made to produce immunological responses in animals such as sheep or rabbits. It is possible to combine the specificity of an immunochemical reaction with the extreme sensitivity of radiotracer detection. Analytical methods based upon these principles have achieved wide applicability in the determination of organic compounds at trace levels. 

In the following discussion, three types of air pollutant analytical data will be examined using principal component analysis and the K-Nearest Neighbor (KNN) procedure. A set of Interlaboratory comparison data from X-ray emission trace element analysis, data from a comparison of two methods for determining lead In gasoline, and results from gas chromatography/mass spectrometry analysis for volatile organic compounds In ambient air will be used as Illustrations. 

Pankow JF, Eigocki MP, Rosen ME, et al. 1988. Adsorption/thermal desorption with small cartridges for the determination of trace aqueous semivolatile organic compounds. Anal Chem 60 40-47. 

Notwithstanding the excellent analytical features inherent in molecular phosphorimetric measurements, their use has been impeded by the need for cumbersome cryogenic temperature techniques. The ability to stabilize the "triplet state" at room temperature by immobilization of the phosphor on a solid support [69,70] or in a liquid solution using an "ordered medium" [71] has opened new avenues for phosphorescence studies and analytical phosphorimetry. Room-temperature phosphorescence (RTF) has so far been used for the determination of trace amounts of many organic compounds of biochemical interest [69,72]. Retention of the phosphorescent species on a solid support housed in a flow-cell is an excellent way of "anchoring" it in order to avoid radiationless deactivation. A configuration such as that shown in Fig. 2.13.4 was used to implement a sensor based on this principle in order to determine aluminium in clinical samples (dialysis fluids and concen-... 

High-Performance Liquid Chromatography for Determination of Trace Organic Compounds in Aqueous Environmental Samples... 

A review of high-performance liquid chromatographic (HPLC) instrumentation, techniques, and methodologies for the determination of trace organic compounds in water is presented. The review includes approaches to sample cleanup or analyte isolation for those compounds likely to be candidates for analysis by HPLC. Column technology, as it contributes to the use of HPLC for trace organic analyses, is discussed. Finally, various techniques for quantitative and qualitative detection of analytes are discussed. 

GRAHAM HPLC Determination of Trace Organic Compounds... 

---