Enhancement solutions

P. M. Bauer, D. J. Hanlon, and W. R. Menking. Process for producing bentonite clays exhibiting enhanced solution viscosity properties. Patent US 5248641, 1993. 

Starting from each of the combined solutions in step 5, use the improvement method to create a set of enhanced solutions. 

If an enhanced solution is better than any member of the reference set, insert it in the reference set and delete the worst member of the set. 

Time-resolved approaches for multi-analyte immunoassays have been described recently. Simultaneous determination of LH, follicle stimulating hormone (FSH), hCG, and prolactin (PRL) in a multisite manual strip format has been reported. 88 Four microtiter wells are attached to a plastic strip, two-by-two and back-to-back, such that the wells can be read on a microtiter plate reader. In a quadruple-label format, the simultaneous quantitative determination of four analytes in dried blood spots can be done using europium, samarium, dysprosium, and terbium. 89 In this approach, thyroid-stimulating hormone, 17-a-hydroxyprogesterone, immunoreactive trypsin, and creatine kinase MM (CK-MM) isoenzyme are determined from dried blood samples spotted on filter paper in a microtiter well coated with a mixture of antibodies. Dissociative fluorescence enhancement of the four ions using cofluorescence-based enhancement solutions enables the time-resolved fluorescence of each ion to be measured through four narrow-band interference filters. 

Silver-enhancing solution (II) 60 mL protective colloid (25% gum arabic or 50% PEG [20,000 mol wt] or PVP), 10 mL 2 M citric acid or sodium citrate, and 850 mg hydroquinone dissolved in 15 mL deionized glass-distilled water mix thoroughly adjust pH to 3.8 immediately before use, add 110 mg silver lactate dissolved in 15 mL deionized glass-distilled water (see Note 2). 

Prepare silver-enhancing solution immediately prior to use, and cover the sections with the solution (see Note 6). 

Commercially available kits are more stable and not as light-sensitive as enhancing solutions prepared in the laboratory. 

The ions from the buffer must be removed, or they will serve as nucleation sites for the silver and increase the background. If rinsing the samples in distilled water will damage the tissue or if the acid pH of the enhancing solution will remove antibodies with low affinities, the samples may be briefly fixed and quenched before rinsing in water and proceeding to the next steps. 

As mentioned previously, the physical state of a solute is susceptible to modifications by interaction with cosolvents. In principle, a cosolvent can enhance solute solubility by changing the solvency of the medium, by direct solute interaction, by adsorption, or by partitioning (Chiou et al. 1986). In a batch experiment testing the effect of humic acid on kerosene dissolution in an aqueous solution, Dror et al. (2000a) found a linear correlation between the amount of humic acid and the amount of kerosene that dissolved (Fig. 6.5). 

Fig. 25. (A) DELFIA (Dissociation Enhanced Lanthanide Fluoro-ImmunoAssay) system. This heterogeneous immunoassay system uses a primary antibody bound to a solid support, to which a variable amount of unlabeled antigen is bound. The secondary antibody is labeled with a non-phospho-rescent lanthanide chelate, which becomes phosphorescent after dissociation from the antibody, due to the addition of an enhancement solution [which typically contains a mixture of sensitizer (typically a (1-diketonate) and micelle inducing surfactant (5). (B) Heterogeneous fluoroimmunoassay using a secondary antibody directly labeled with a phosphorescent lanthanide chelate.

Rinse sections in high-quality distilled water to remove all traces of chloride ions and other impurities that might contaminate the silver-enhancing solution. Some commercial enhancement solutions are reported to be resistant to contamination, the user should evaluate this carefully, especially if high levels of nonspecific background are encountered... 

Problems with nonspecific background silver deposition. Background silver deposition may be owing to the use of poor-quality antibodies, incorrectly diluted antibodies, old silver-enhancing solutions, poor-quality distilled water, or incorrect silver-enhancement times The silver-enhancement procedure is tempera-... 

In order to increase the sensitivity and selectivity of detection, a number of UV-absorbing or fluorescent derivatives have been prepared. Several reasons can be given for the use of deriva-tization in chromatography to enhance solute volatility (GC), to enhance separation, and to enhance detectability. The selection of a derivative can often become much more difficult than the actual derivatization itself. In all areas of chromatography these effects have been succesfully applied to difficult or otherwise impossible separation. 

Santagada, V., Perissutti, E., Fiorino, F., Vivenzio, B. and Caliendo, G., Microwave enhanced solution synthesis... 

Since the experimental conditions for the traditional Biginelli reaction are quite straightforward, small libraries of DHPMs are readily accessible by parallel synthesis. Along these lines the generation of a 140-member single compound DHPM library by combination of 25 aldehydes, 6 ureas/thioureas, and 7 acetoacetates or acetoamides under standard reaction conditions has been reported [123, 124]. More rapid approaches make use of microwave-enhanced solution-phase protocols [88, 89, 125]. Apart from these conventional solution-phase methods, it is also possible to employ polymer-supported reagents to aid in the purification and workup protocol. Polymer-assisted solution-phase chemistry using polymer-supported... 

Problems with nonspecific background silver deposition background silver deposition may result from the use of poor-quality antibodies, incorrectly diluted antibodies, old silver-enhancing solutions, poor-quality distilled water, or incorrect silver enhancement times. The silver enhancement procedure is temperature dependent and where laboratory temperatures vary a lot, especially at different times of the year, it is useful to construct a standardized temperature-enhancement time graph and keep it readily available at the bench (Fig. 3). As an example, adequate silver enhancement may take only 5 min at 25°C whereas the same result may take up to 15 min to obtain at 15°C. Enhancement times may be controlled more precisely by storing the enhancer components in the refrigerator at... 

Reactive absorption represents a process in which a selective solution of gaseous species by a liquid solvent phase is combined with chemical reactions. As compared to purely physical absorption, RA does not necessarily require elevated pressure and high solubility of absorbed components because of the chemical reaction, the equilibrium state can be shifted favorably, resulting in enhanced solution capacity (17). Most RA processes involve reactions in the liquid phase only in some of them, both liquid and gas reactions occur (18,19). 

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