Luminescence procedure

Whitehead, T. P, Thorpe, G. H G, Carter, T. J. N, Groucutt, C., and Kricka, L J. (1983) Enhanced luminescence procedure for sensitive determination of peroxidase-labeled conjugates in immunoassay. Nature 305, 158,159. 

Luminescence procedures present a powerful method for the determination of diffusion constants for a variety of penetrants in polymer systems, and have been reviewed recently (9). 

Flow-through luminescent procedures have several advantages continuous flow operation, easier automation, improved precision, and selectivity by using online separation chemistries. The drawback that water has in SPP batch procedures, especially with paper, disappears with continuous procedures, making it possible to obtain signals from aqueous flows (Figure 3). 

Three related types of optical methods are considered in this chapter molecular fluorescence, phosphorescence, and chemiluminescence. In each of these methods, molecules of the analyte are excited to produce a species whose emission spectrum provides information for qualitative or quantitative analysis. The methods are known collectively as molecular luminescence procedures. 

This method works well when the polymer can be studied as a self-supporting film. However, in many cases, films cannot be easily obtained from polymers, or measurements are required at temperatures above the glass transition or in the melt, for example. In this case, a gas chromatographic procedure has been developed by Guillet and coworkers which is useful in measuring both solubilities and diffusion constants for small molecules [14-16]. Recently, luminescence procedures have been developed which supplement data obtained by more classical methods. 

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 second procedure is to measure the luminescence intensities at various Ca2+ concentrations and plot log (light intensity) against —log [Ca2+] for each aequorin. Examples of this method are shown in Fig. 4.1.14. This method provides more detailed information on the sensitivity of each aequorin. Generally, an increase in Ca2+ sensitivity shifts the curve to the left. 

Definition and Uses of Standards. In the context of this paper, the term "standard" denotes a well-characterized material for which a physical parameter or concentration of chemical constituent has been determined with a known precision and accuracy. These standards can be used to check or determine (a) instrumental parameters such as wavelength accuracy, detection-system spectral responsivity, and stability (b) the instrument response to specific fluorescent species and (c) the accuracy of measurements made by specific Instruments or measurement procedures (assess whether the analytical measurement process is in statistical control and whether it exhibits bias). Once the luminescence instrumentation has been calibrated, it can be used to measure the luminescence characteristics of chemical systems, including corrected excitation and emission spectra, quantum yields, decay times, emission anisotropies, energy transfer, and, with appropriate standards, the concentrations of chemical constituents in complex S2unples. 

Several solid surfaces, such as filter paper, sodium acetate, and silica gel chromatoplates with a polyacrylate binder, have been used in solid-surface luminescence work (1,2). Experimentally it is relatively easy to prepare samples for analysis. With filter paper, for example, a small volume of sample solution is spotted onto the surface, the filter paper is dried, and then the measurement is made. In many cases, an inert gas is passed over the surface during the measurement step to enhance the RTF signal. For powdered samples, the sample preparation procedure is somewhat more involved. Commercial instruments can be readily used to measure the luminescence signals, and a variety of research instruments have been developed to obtain the solid-surface luminescence data (1,2). 

Room-temperature fluorescence (RTF) has been used to determine the emission characteristics of a wide variety of materials relative to the wavelengths of selected Fraunhofer lines in support of the Fraunhofer luminescence detector remote-sensing instrument. RTF techniques are now used in the compilation of excitation-emission-matrix (EEM) fluorescence "signatures" of materials. The spectral data are collected with a Perkin-Elraer MPF-44B Fluorescence Spectrometer interfaced to an Apple 11+ personal computer. EEM fluorescence data can be displayed as 3-D perspective plots, contour plots, or "color-contour" images. The integrated intensity for selected Fraunhofer lines can also be directly extracted from the EEM data rather than being collected with a separate procedure. Fluorescence, chemical, and mineralogical data will be statistically analyzed to determine the probable physical and/or chemical causes of the fluorescence. 

The synthesis of luminescent organoboron quinolate polymers (21) (Fig. 15) via a three-step procedure starting from a silylated polystyrene has been communicated. The synthesis was initiated by the highly selective borylation of poly (4-trimethylsilylstyrene) (PS-Si), followed by the replacement of the bromine substituents in poly(4-dibromoborylstyrene) (PS-BBr) with substituted thienyl groups (R = H, 3-hexyl, 5-hexyl). In the final step, the 8-hydroxyquinolato moiety was introduced. The hexyl-substituted polymers efficiently emitted light at 513-514nm upon excitation at 395 nm.40... 

Procedure The fluorescence of the objects, which lie on the object glasses (slices) and excited by ultra-violet (360-380 nm) or violet (400-420 nm) light, may be seen in luminescent microscope with multiplication of objectives x 10,20,40 or with water immersion x 85, or with immersion oil x 60 and 85. ... 

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