Phenol blue density

Figure 5. E of phenol blue in ethylene vs. density (0= 25 °C, A= 10 °C, and ---- is calculated E using Equation 5).

Ground State Recovery of Phenol Blue in Fluids near the Gas-Liquid Critical Density Yoshifumi Kimura and Noboru Hirota... 

We have made a sub-picosecond pump-probe transient absorption study on Phenol Blue at 308 K in trifluoromethane near the gas-liquid critical density and at the high density (about twice of the critical density) where small amount of 2,2,2-trifluoroethanol is added as cosolvent. The ground state hole created by the pump pulse is mostly broadened by about 1 ps, and we could not detect any meaningful density effect on this process. 

For these purposes we have studied the solvatochromic dye of Phenol Blue (PB, Scheme 1) in trifluoromethane (CF3H) near the critical density. Although betaine-30 is more preferable for the comparison with liquid solvent, it was impossible due to the extremely low solubility of betaine-30 to CF3H. PB is more soluble in CF3H, and has absorption around 560 nm which is accessible by our laser system. Unfortunately the photophysics of PB has not been studied until now even in liquid solution. Therefore we have also studied the ground state recovery in several liquid solvents. According to the theoretical calculation, the charge... 

Eckert et al. (1) interpreted partial molar volume data for supercritical solutions as indicating the collapse of 100 solvent molecules about a solute molecule. Kim and Johnston (2) interpreted the solvent shift in the UV absorption of phenol blue dissolved in supercritical ethylene to suggest a local solvent density surrounding a solute molecule more than 50% greater... 

The purpose of these scales is to provide a guide for choosing SCF solvents and co-solvents to achieve a desired solvent strength, for example in a separation or reaction process. An example of a solvatochromic scale is presented in Figure 1 for the UV-vis absorption of phenol blue in ethylene as a function of density at two temperatures (S). The scale is defined as the transition energy, Ej = he/ Xmax where Xmax is the wavelength of maximum absorption. 

Figure 4. Comparison of local density and bulk density versus pressure based on the solvatochromism of phenol blue in ethylene at 25 C (data from ref. 8.).

Kim and Johnston made a similar observation of nonlinear density dependence for the shift in the absorption spectral maximum of phenol blue in... 

Figure 3 Transition energy ( j) and isothermal compressibility vs. density for phenol blue in ethylene (O) 25°C, (A) 10°C, (-----) calculated E t. (From Ref. 26.)...

T Yamaguchi, Y Kimura, M Hirota. Solvent and solvent density effects on the spectral shifts and the bandwidths of the absorption and the resonance raman spectra of phenol blue. J Phys Chem 101 9050, 1997. 

Figure 5 Transition energy of phenol blue in SC 1,1-difluoroethane as a function of the bulk density. Measured values (symbols) and values expected on the basis of the dielectric constant of the bulk fluid (line) reprinted from Ref. 15...

Shown in Figure 6 is in vitro cytotoxic activity of PIPAAm-PBMA micelles loaded with ADR or micelles without ADR at 29°C (below the LCST) and at 37°C (above the LCST) compared with that of free ADR. In vitro cytotoxic activity was measured using bovine aorta endothelial cells. Bovine aortic endothelial cells were obtained as previously reported using dispase for cell dissociation from freshly harvested bovine aorta [13]. The cells plated at a density of 3 x cells/well, were exposed with free ADR or micelles loaded with ADR at below and above the LCST for 5 days. In order to assay cytotoxicity of the free ADR or micelles loaded with ADR, culture medium was replaced with 10% FBS-supplemented phenol red-free DMEM containing 10% alamar Blue, a dye that is subject to reduction by cytochrome c activity and changes the color from blue to red [38]. After 4-hour incubation, reduction of the dye was estimated by absorbance at 560 and 600 nm. PIPAAm-PBMA polymeric micelles loaded with ADR showed higher cytotoxic activity than that of free ADR at 37°C (above the LCST)... 

Spiropyran merocyanine specffa shift markedly to the blue as the solvent polarity increases [4,25], as shown in Fig. 7a for 6,8-dinitro-BIPS merocyanine. This is generally accepted to imply that they have a zwitterionic character caused by the donation of electron density from the indoline nitrogen to the phenolic C9 oxygen [4,25]. The rational behind this assignment to the zwitterion is based simply on the fact that if the zwitterion is in the highest occupied molecular orbital (HOMO) state, then the corresponding quinoidal resonant form is in the lowest unoccupied molecular orbital (LUMO) state and changing the solvent to a more polar one... 

The measurement of optic density, absorbance, is widely used to determine wine color (Volume 2, Section 6.4.5) and total phenolic compounds concentration (Volume 2, Section 6.4.1). In these works, the optic density is noted as OD, OD 420 (yellow), OD 520 (red), OD 620 (blue) or OD 280 (absorption in ultraviolet spectrum) to indicate the optic density at the indicated wavelengths. 

Determine the optical density of the indophenol blue colour produced between 15 and 30 minutes after addition of the phenol and sodium hypochlorite reagents. 

This method involves oxidation-deduction reactions in which the phenolate ion is oxidized while [Fe(CN)6] ion is reduced. It is a popular method to quantify total phenoUcs because it is simple, rapid, and with little interferences by nonphenolic compounds. " Critical for the successful use of this assay are temperature, pH, and order in which reagents are added, since this affects the formation of Fe4[Fe(CN)e]3 (Pmssian Blue). However, this assay presents two important shortcomings that have to be taken into account for the adequate interpretation of results the formation of a precipitate after short incubation periods and the increase in color density with time. 

The concentration of a protein can be determined by various colorimetric methods including the old standard Folin—phenol reagent assay of Lowry (79) or the new standard Coomassie blue R-250 method of Bradford (80) or bicin-choninic acid (BCA) assay. Silver stain (108) and gold stain are also widely used to identify and quantitate proteins with a 10-50 times greater sensitivity than Coomassie blue staining. Once a reliable estimate of the protein concentration is obtained, the UV absorptivity of the known protein can be used to determine unknown concentrations of the same protein. From the Beer—Lambert law, A(x) = o% lJI) = where is the absorbance (or optical density) at the... 

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