Detection luminescence

The opportunity of use of a ternary complex of ions Eu(III) with oxatetracycline (OxTC) and citrat-ions (Cit) for luminescent detection of OxTC in milk after chromatographic isolation is shown. 

The aqueous micellai solutions of some surfactants exhibit the cloud point, or turbidity, phenomenon when the solution is heated or cooled above or below a certain temperature. Then the phase sepai ation into two isotropic liquid phases occurs a concentrated phase containing most of the surfactant and an aqueous phase containing a surfactant concentration close to the critical micellar concentration. The anionic surfactant solutions show this phenomenon in acid media without any temperature modifications. The aim of the present work is to explore the analytical possibilities of acid-induced cloud point extraction in the extraction and preconcentration of polycyclic ai omatic hydrocai bons (PAHs) from water solutions. The combination of extraction, preconcentration and luminescence detection of PAHs in one step under their trace determination in objects mentioned allows to exclude the use of lai ge volumes of expensive, high-purity and toxic organic solvents and replace the known time and solvent consuming procedures by more simple and convenient methods. 

The very first spectroscopic instruments, from Newton s prism and pinhole to Frauenhofer s simple spectroscope, were constructed to observe luminescence. Even though the great sensitivity of luminescence detection seemed to promise that luminescence would become an important tool for chemical analysis, the fact is that absorption spectroscopy was the first spectroscopic technique to be widely used. At first glance, this may seem surprising since absorption spectroscopy is inherently less sensitive and had to await the development of more complex instrumentation, especially, electronically amplified detection. 

Cobalt (II) has been determined by online measurements on seawater which has been passed through a column containing 8-quinolinol immobilised on silica gel, followed by chemical luminescence detection [244]. 

The variety of assays reported here displays the great versatility of luminescent detection systems. As already described, in all luminescent systems the main advantages are the high sensitivity and specificity, which reduce to the minimum the sample treatment, and the ease of use of the reagents and the luminometer. Immobilized systems greatly reduce the cost per assay on the other hand, their preparation requires expertise, especially in the surface activation step on nylon tubes. 

This chapter outlines the chemical principles for luminescent detection of target DNA in hybridization and quantitative assays that utilize the above-mentioned chemiluminogenic and bioluminogenic reagents. 

Sensors based on integrated retention and luminescence detection... 

DeJong G, Kwakman P. Chemi-luminescence detection for high-performance liquid-chromatography of biomedical samples. Journal of Chromatography. Biomedical Applications 492, 319-343, 1989. 

IR luminescence detected in ZrSi04-Cr has an excitation band peaking at 920 nm. Its luminescence spectrum at 300 K (Fig. 5.38) is characterized by a relatively unresolved broad band peaking at 1,200 nm. It is very similar to Cr luminescence in silicates, especially in forsterite except for a very short decay time shorter than the time resolution of our detection system about 200 ns. It is not suitable for Cr with a much longer decay in the ps range (Boulon 1997). Luminescence at lower temperatures is much more intensive and spectra are characterized by several strong narrow hnes with very short decay which appear already at 100 K. Once again, it is rather unusual for Cr +. 

The real limitation of detection in spectrofluorimetry is not the sensitivity of the detector, but rather the stray light which result from imperfections of the monochromators and emissions by impurities in the solvents. The limiting quantum yields of luminescence detection are of about 10-4 in optimal conditions. 

The use of europium chelates, with their unusually long fluorescence decay times, as labels for proteins and antibodies has provided techniques that are referred to as time-resolved fluoroimmunoassays (TRFIA). Fluorophores as labels for biomolecules will be the topic of Sect. 3. Nevertheless, TRFIAs always have to compete with ELISA (enzyme-linked immunosorbent assays) techniques, which are characterized by their great versatility and sensitivity through an enzyme-driven signal amplification. Numerous studies have been published over the past two decades which compare both analytical methods, e.g., with respect to the detection of influenza viruses or HIV-1 specific IgA antibodies [117,118]. Lanthanide luminescence detection is another new development, and Tb(III) complexes have been applied, for instance, as indicators for peroxidase-catalyzed dimerization products in ELISAs [119]. 

Ruthenium complexes have been applied successfully to the luminescent detection of proteins on blotting membranes like nitrocellulose [160]. The bipyridyl and phenanthroline complexes modified with aminoreactive NHS-ester or isothiocyanate groups are commercially available [161]. An even higher sensitivity and lower detection limit can be obtained by encapsulating... 

Wittmann, C. and P.-Y. Schreiter (1999). Analysis of terbuthylazine in soil samples by two test strip immunoassay formats using reflectance and luminescence detection. J. Agric. Food Chem., 47 2733-2737. 

Houten KAV, Heath DC, Pilato RS. Rapid Luminescent detection of phosphate esters in solution and the gas phase using (dppc)Pt S2C2(2-pyridyl)(CH2CH2OH). J Am Chem Soc 1998 120 12359-60. 

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