Fluorescence function

Some commercially available detectors have a number of detection modes built into a single unit. Fig. 2.4o is a diagram of the detector used in the Perkin Elmer 3D system, which combines uv absorption, fluorescence and conductivity detection. The uv function is a fixed wavelength (254 nm) detector, and the fluorescence function can monitor emission above 280 nm, based on excitation at 254 nm. The metal inlet and outlet tubes act as the electrodes in the conductance cell. The detection modes can be operated independently or simultaneously, using a multichannel recorder. In the conductivity mode, using NaCl, a linear range of 103 and a noise equivalent concentration of 5 x 10 8 g cm-3 have been obtained. 

Synthesis of Fluorescent Functional Ras-Proteins by a Combined Organic Synthesis and Molecular Biology... 

Liu J, Zhang Y, Yang T, Ge Y, Zhang S, Chen Z, Gu N (2009) Synthesis, characterization, and application of composite alginate microspheres with magnetic and fluorescent functionalities. J Appl Polym Sci 113 4042 1051... 

Fluorescence Function It can monitor emission above 280 nm, based on excitation at 254 nm,... 

The detection of contamination with mercury is a very serious issue due to the extreme toxicity and ease of reaction of this heavy metal. Mercury is commonly used in many everyday applications, such as thermometry, barometry or scientific apparatus. Therefore, it is important to note the development of a fluorescent IIP membrane for detection of mercury [63], This membrane was based on the combination of two fluorescent functional monomers, namely 4-vinyl pyridine and 9-vinylcarbazole. Binding of Hg2+ was proposed to be based on complexation of the metal ion with lone pairs of both pyridine and carbazole. The IIP membrane was capable of recognizing Hg2+in the linear range of concentrations from 5 x 10 7 to 1 x 10 4 M. Selectivity of the chemosensor was studied for a wide group of possible competitive ions and the chemosensor responded to all of them in the presence of a fixed amount of Hg2+ at 1 x 10 5 M. Nevertheless, the highest influence on recognition properties was observed in the presence of Cu2+ (4.87%) and Pb2+ (4.57%), which are still acceptable values for the successful detection of Hg2+. This progress stimulates further development of the MIP detection of ions. 

The sensitivity of the UV absorption function is about 1.7 x 10" g/ml for toluene with a linear dynamic range of about 1.5 x lo. These specifications compare well with those expected for a fixed wavelength UV detector. The fluorescence function provides a sensitivity of about... 

In a short communication, Cooper et al. [28] report the utilisation of two novel fluorescent functional monomers (Fig. 20.10) in EDMA-based MlPs. Initially, a polymerisable phenolic compound was treated with cholesterol chloroformate (as per Whitcombe et al. [29]) and used to prepare a covalently imprinted polymer. Details are lacking, but this procedure was not successful both the imprinted and the non-imprinted polymers had a similar affinity for cholesterol and no changes in... 

Fig. 20.10. Fluorescent functional monomers for covalent and non-covalent imprinting.

Wang and co-workers [53] have succeeded in constructing a novel sensor based on the displacement of a small, structurally unrelated quencher from a MIP comprising a fluorescent functional monomer (Fig. 20.20). The principle of detection relies upon the enhanced fluorescence observed upon displacement of the quencher, p-nitrobenzaldehyde, from the L-tryptophan (r-Trp) binding sites within the polymer. 

Fig. 20.20. The template (L-tryptophan) and the fluorescent functional monomer used in this study.

As outlined earlier, our fluorescent sensors far are hybrid systems made by attaching ionophores (of high selectivity for K ) to efficient fluorescing groups. In designing these hybrid systems, it is important not to compromise either the selectivity of the ionophore or the efficiency of the fluorescing function. For this reason, we decided not to use natural antibiotics such as valinomycin in our hybrid systems. Valinomycin shows an unusually high selectivity for (9.101. However, the... 

Figure 11.3 SEM images of PANI-SA/RhB synthesized using different concentrations of RhB (a) 0 M, (b) 1 mM, (c) 5 mM, and (d) 10 mM. Synthetic conditions [An]=0.2 M, [An]/ [SA]—1 1, and [An]/[APS]= 1 1. (Reprinted with permission from Macromol. Rapid Common., Hollow Polyaniline Microspheres with Conductive and Fluorescent Function by Lijuan Zhang, Meixiang Wan and Yen Wei, 27, 11, 888-893. Copyright (2006) Wiley-VCH)...

L.J. Zhang, M. Wang, and Y. Wei, Hollow polyaniline microspheres with conductive and fluorescent function, Macromol. Rapid Commun., 27(11), 888-893 (2006). 

Minta, A. Tsien. R.Y. Fluorescent indicators for cytosolic sodium. J. Biol. Chem. 1989, 264, 19449-19457. de Silva, A.P. Gunaratne, H.Q.N. Gunnlaugs.son. T. Nieuwenhuizen, M. Fluorescent switches with high selectivity towards sodium ions Correlation of ion-induced conformation switching with fluorescence function. Chem. Commun. 1996. 1967-1968. 

Turkewitsch, P. Wandelt, B. Darling, G.D. Powell, W.S. Fluorescent functional recognition sites through molecular imprinting. A polymer-based fluorescent chemosensor for aqueous camp. Anal. Chem. 1998, 70,2025-2030. 

The sensitivity of the UV absorption function was 1.7 x 10 g/ml of toluene with a linear dynamic range of about 1.5 x 10. These specifications compare well with those of the standard fixed wavelength UV detector. The fluorescence function provided a sensitivity of 2.5 x 10 g/ml for dansyl iso-leucine and a linear dynamic range of 1.2 x 10. Finally, the sensitivity of the conductivity function to sodium chloride was shown to be 5 x 10 g/ml with a linear dynamic range of 3 x 10. The response indices were 0.975, 0.95, 1.042 for the UV function, the fluorescence function and the conductivity function respectively. The dispersion of the cell was small, equivalent to a standard deviation of about 2.8 iiU... 

Multi-functional detectors monitor the column eluent by the measurement of more than one physical or chemical property simultaneously, employing a single sensing cell. To date, three bifunctional detectors and one trifunctional detector have been described. The three bifunctional detectors have combined UV absorption and fluorescent detection, UV absorption and electrical conductivity detection and UV absorption and refractive index detection. The latter uniquely combines a bulk property detector with a solute property detector producing, at least in theory, the nearest approach to a universal detector. The trifunctional detector incorporates UV absorption, electrical conductivity and fluorescence functions. Multi-functional detection provides detector versatility and a means of confirmir solute identity. Such detectors have to be designed, so that the performance specifications are not seriously compromised, and the cell and eluent conduits do not contribute significantly to peak dispersion. 

Hoshino, T. Shirota, N. Asakawa, A. Compound having fluorescent functional group and method for producing polymer of the same. PCX hit. Appl. WO 2009011427, 2009. 

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