Glycerol concentration determination

Fig. 4 Polymerization of GTP-tubulin in 3.4 M glycerol, lOmM sodium phosphate, ImM EGTA, ImM GTP, pH 6.7 buffer at 37°C measured by sedimentation. Solid circles, pelleted tubulin hollow circles, tubulin in the supernatant. The critical concentration determined is 5.3 pM under this total concentration no tubulin is pelleted while over this total concentration all tubulin in excess is pelleted...

This is a very widely used determination, but suffers from the drawback of matrix effects, for instance if the wine contains atypical concentrations of glycerol, as was first reported by Bouvier (1986). 

Resuspend the pellets in 10 mM Tris-HCl, pH 8.0, 5% (w/v) glycerol, 1 mM EDTA, 0.5 mM EGTA, and dialyze overnight in the same buffer. After dialysis, remove 50-100 /il for DNA concentration determination and freeze the rest of the chromatin in aliquots at -80°C. For determining the DNA concentration, the sample is treated with RNase A and proteinase K as described below in Section IV,B,2. 

Ackermans, M.T., Ruiter, A.F.C., and Endert, E. (1998) Determination of glycerol concentrations and glycerol isotopic enrichments in human plasma by gas chromatography/mass spectrometry. Analytical Biochemistry, 258, 80-86. 

Flakoll, RJ., Zheng, M.,Vaughan, S., and Borel, M.J. (2000) Determination of stable isotopic enrichment and concentration of glycerol in plasma via gas-chromatography-mass spectrometry for the estimation of lipolysis in vivo. Journal of Chromatography B, 744,47-54. 

The concentration of distilled glycerol is easily determined from its specific gravity (15) by the pycnometer method (16) with a precision of 0.02%. Deterrnination of the refractive index also is employed (but not as widely) to measure glycerol concentration to 0.1% (17). 

The changes in osmotic coefficients with temperature and concentration make it difficult to solve the above equations accurately, but accurate determinations of the composition and relative amounts of the concentrated liquid and ice can be made from phase diagrams which are plots of the freezing points of solutions versus their concentration. From these, it is possible to determine the exact NaCl concentration at any temperature. Examples are shown in Figure 9 for solutions of 0 to 2.0 M glycerol in 0.15 M NaCl. This figure nicely illustrates how the presence of glycerol reduces the concentration of NaCl in the residual unfrozen solution. 

Initially we examined the adsorption of the primary individual species, glycerol and PG. The amount of material adsorbed was determined by differences in solution concentration over extended exposure of solutions to activated carbon support. The results indicate that the PG pore concentration can be three- to five-fold... 

Note Data represent the mean S.E. (n = 3). MW, molecular weight P0/w, octanol-to-water partition coefficient CLapp, apparent membrane permeability clearance SI, midgut area of the small intestine NA, not available or applicable. Absorption was evaluated in our laboratory using the closed loop of the rat intestine in situ (urethane anesthesia, 1.125 g/4.5 ml/kg, i.p.) in 60 min for riboflavin and L-camitine and 30 min for the others. For those that are transported by carriers in part (riboflavin and glycerol in both colon and SI, and L-carnitine, 5-fluorouracil, and cephradine in SI), absorption was evaluated at higher concentrations where the contribution of carrier-mediated transport is negligible. Values of P0/w were obtained from a report by Leo et al. [30] except for that of D-xylose, which was determined in our laboratory. a Data by single-pass perfusion experiments. b Unpublished data from our laboratory. 

The outer and core radii were determined from optical resonance measurements using Mie theory solutions (Aden and Kerker, 1951 Bohren and Huffman, 1983) for concentric spheres to interpret the resonance spectra. Figure 36 presents some of the data of Ray et al. for a pure component glycerol droplet and for a coated droplet having an initial coating thickness given by yo = 0-321. Here y is a reduced thickness defined by y = (a - aj/a. 

PD is the least toxic product in the glycerol fermentation, but nevertheless determines the achievable final concentration. A final concentration of propanediol around 60-70 g/1 is usually achieved with wild-type strains. More than 85 g/1 1,3-PD can be produced with these microorganisms in special fed-batch fermentations (unpublished results). With externally added 1,3-PD,... 

Determination of B and D Values for Solutes Relevant to Membrane Concentrations of Organic Pollutants. A compilation of the data on B and D values for a large number of organic solutes was made (11) in which glycerol was chosen as a reference solute for both CA and... 

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