Organic trace analysis

Solid-surface room-temperature phosphorescence (RTF) is a relatively new technique which has been used for organic trace analysis in several fields. However, the fundamental interactions needed for RTF are only partly understood. To clarify some of the interactions required for strong RTF, organic compounds adsorbed on several surfaces are being studied. Fluorescence quantum yield values, phosphorescence quantum yield values, and phosphorescence lifetime values were obtained for model compounds adsorbed on sodiiun acetate-sodium chloride mixtures and on a-cyclodextrin-sodium chloride mixtures. With the data obtained, the triplet formation efficiency and some of the rate constants related to the luminescence processes were calculated. This information clarified several of the interactions responsible for RTF from organic compounds adsorbed on sodium acetate-sodium chloride and a-cyclodextrin-sodium chloride mixtures. Work with silica gel chromatoplates has involved studying the effects of moisture, gases, and various solvents on the fluorescence and phosphorescence intensities. The net result of the study has been to improve the experimental conditions for enhanced sensitivity and selectivity in solid-surface luminescence analysis. 

Solid-surface luminescence analysis involves the measurement of fluorescence and phosphorescence of organic compounds adsorbed on solid materials. Several solid matrices such as filter paper, silica with a polyacrylate binder, sodium acetate, and cyclodextrins have been used in trace organic analysis. Recent monographs have considered the details of solid-surface luminescence analysis (1,2). Solid-surface room-temperature fluorescence (RTF) has been used for several years in organic trace analysis. However, solid-surface room-temperature phosphorescence (RTF) is a relatively new technique, and the experimental conditions for RTF are more critical than for RTF. 

Interactions in Solid-Surface Luminescence Temperature Variation. Solid-surface luminescence analysis, especially solid-surface RTF, is being used more extensively in organic trace analysis than in the past because of its simplicity, selectivity, and sensitivity (,1,2). However, the interactions needed for strong luminescence signals are not well understood. In order to understand some of the interactions in solid-surface luminescence we recently developed a method for the determination of room-temperature fluorescence and phosphorescence quantum yields for compounds adsorbed on solid surfaces (27). In addition, we have been investigating the RTF and RTF properties of the anion of p-aminobenzoic acid adsorbed on sodium acetate as a model system. Sodium acetate and the anion of p-aminobenzoic acid have essentially no luminescence impurities. Also, the overall system is somewhat easier to study than compounds adsorbed on other surfaces, such as filter paper, because sodium acetate is more simple chemically. 

Solid-surface luminescence analysis is a useful approach for organic trace analysis because of its simplicity, sensitivity, and selectivity. It will continue to be used in environmental analysis and other areas not only for the reasons mentioned above but also because it is readily adaptable to field work. By developing a fundamental understanding of the interactions responsible for strong RTF and RTF signals, the advantages and disadvantages of the luminescence approach will be more specifically defined in the future. 

J. F. Lawrence, "Organic Trace Analysis By Liquid Chroaatography", Academic Press, New York, NY, 1981. 

K. Beyerman, "Organic Trace Analysis", Ellis Horwood, Chichester, UK, 1984. 

ORGANIC TRACE ANALYSIS, SPECIATION Environmental protection, food inspection... 

Danzer K, De la Calle D, Thiel G, Reichenbacher M (1999) Classification of wine samples according to origin and grape varieties on the basis of inorganic and organic trace analysis. Am Lab 31 26... 

J.E. Lawrence, in Organic Trace Analysis by Liquid Chromatography (J.E. Lawrence, Ed.), Academic Press, New York (1981). 

Beyermann, K., Organic Trace Analysis, Halsted Press (of John Wiley Sons), New York, 1984. 

To meet the high demands of organic trace analysis,21 GC columns have been subject to continuous refinement. This refers not only to the reduction in diameter of the nowadays almost exclusively used capillary columns (separation efficiency increases with decreasing capillary diameter), but also reflects the development in stationary phase technology In order to reduce column bleed (which is essential for mass spectrometric detection), highly cross-linked stationary phases are used to... 

Organic trace analysis Automated extraction procedure [458]... 

Ballschmiter K (1983), Pure Appl. Chem. 55 1943-1956.. .Sample treatment techniques for organic trace analysis"... 

J. F. Lawrence, Organic Trace Analysis by Liquid Chromatography, London, Academic Press, 1981. N. A. Parris, Instrumental Liquid Chromatography, 2nd Edn, Amsterdam, Elsevier, 1984. 

The problems increase when the analyzed object contains other species with chemical properties similar to those of the analyte. Often there are no specific procedures for a given compound, and the analytical process should start with separation procedures. Among these are, in the first line, various useful chromatographic procedures, which constitute a very important component of the whole analytical process. Therefore, the rapid progress in organic trace analysis in the second half of the twentieth century was coimected with the development of chromatography and physical methods for species identification. 

These comments indicate the difficulty of the task of organic trace analysis. It is also necessary to mention that confirmation of the quality of the determination is more difficult than for trace inorganic analysis (where certified reference materials can be used), because of the greater variety of analytes and their chemical instability. 

Beyermann, K. Organic Trace Analysis. E. Horwood, Chichester (1984)... 

Chamberlain, J. (1985) Analysis of Drugs in Biological Fluids, CRC Press, Boca Raton, FL. Beyermann, K. (1984) Organic Trace Analysis, Ellis Horwood, Chichester. 

Mass spectrometric detection, which is widely used in organic trace analysis, allows sensitive and selective determinations, but high cost and the unresolved interfacing problems limit its application (e.g. ). 

The study of the detector s response with solution(s) can be subdivided into individual steps with growing complexity. This is interesting in particular for complex procedures encountered in organic trace analysis [23,24]. For inorganic trace analysis, calibration solutions should be prepared preferably from pure metals or oxides rather than salts [22]. 

It is possible to produce artificial matrix materials [12]. Such materials can be prepared on a mass basis by weighing all components both to mimic the matrix composition and the content of trace elements or trace organic substances. The materials could help to have matrix materials available for which the exact contents and composition are known. As a consequence it would be, in theory, possible to certify them on a mass basis and validate methods with highly traceable materials. In organic trace analysis this would circumvent the unknown extraction step. In reality, this is much more difficult to achieve than can be expected. The real matrix composition of many materials is unknown — in particular for environment samples. The physico-chemical status of the various substances depends on the history of the material. Therefore, various natural samples of expected similar composition are different in behaviour. In addition, when preparing mixtures of solid components, losses cannot be excluded and unfortunately are not quantifiable. Attempts have been made where losses were demonstrated but not quantified [12]. Therefore, materials certified for matrix composition and analyte content on a mass basis do not yet exist or are not of real use for method validation by routine laboratories. They may be of interest for laboratories active in the field of fundamental research in chemical metrology where smaller quantities of material are handled. 

The real difficulties remain in the determination of U. It is relatively simple to determine the method uncertainty of nondestructive analysis as repeated measurements can be performed on the same sample [39]. It is far more difficult with destructive methods and in particular in organic trace analysis. In the latter case, all the steps in the procedure rarely allow one to achieve a repeatability with a relative standard deviation of less than several percent. The methods often require a large sample intake as samples of a few milligrams are not easy to handle in extraction systems. 

Analysis Materials testing (X-ray examination) indicator and tracer methods radiochemical and biochemical labelling and trace analysis organic trace analysis (BCD) activation analysis... 

Lawrence, J.F. "Organic Trace Analysis by Liquid Chromatography" Academic Press New York, 1981 Chap. 5. 

SPLS is very sensitive and selective for organic trace analysis. Detection limits of a nanogram or even a picogram can be obtained. The methodology is simple, inexpensive, relatively precise (2-20%), relatively rapid, can handle small samples, and can be very selective in mixture analysis when solid-phase fluorescence (SPF) and solid-phase phosphorescence (SPP) are combined or when using derivative, synchronous, or time-resolved SPLS. Additionally, SPLS is well suited to being combined directly with both thin-layer and paper planar chromatography. 

Recent decades have witnessed significant advances in the efficiency and productivity of instrumental methods in the field of organic trace analysis. Chromatographic and spectroscopic methods in particular have improved greatly with respect to sensitivity. There has also been constant improvement in selectivity, to the point where some samples can now be subjected to analysis without prior preparation, although this is certainly not true in the majority of cases. The goal of sample preparation in organic trace analysis is to isolate the analyte from the sample matrix and then concentrate it and convert it into a form suitable for analysis by the selected method. 

In the context of organic trace analysis, appropriate stabilization and storage precautions are a function of the nature of the analyte and its concentration, To avoid contamination by ambient air and dust, all operations should be conducted under clean-room conditions (clean-bench environment). It is of paramount importance to assure that contamination from vessels, covers, septa, and stabilizers is rigorously excluded. 

Currently, ecological research and routine analysis relevant to the environment provide trace analysis with imporant stimuli. At the same time, the centers of attention are shifting more and more from element trace analysis to organic trace analysis. 

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