Diffusion chromatography

Castles, M.A. Azarraga, L.V. Carreira, L.A. Continuous on-line interface for reversed-phase microbore high performance liquid chromatography/diffuse reflectance infrared fourier transform analysis. Appl. Spectrosc. 1986, 40, 673-680. 

Spain, J. D. Precipitation Chromatography. Diffusion and Precipitation of Metal Sulfides on Agar Gel Columns. Analytic. Chem. 32, 1622 (1960). 

A survey of characterization methods for linear and branched nonionic polyacrylamides is given in reference 5. Gel-permeation chromatography, diffusion and sedimentation, intrinsic viscosity, and light scattering are discussed emphasizing some difficulties encountered in obtaining consistent data. Characterization of anionic polyacrylamides used in oil recovery by ir spectroscopy, 13C-nmr, tga, and x-ray diffraction is described in reference 8. 

In gas chromatography diffusion always plays a part in the broadening of component band. Consequently the shape and width of diffusion zone of a component are identical with those of its elution peak. The broadening due to diffusion represents the minimum width of the peak. 

Tihminlioglu, F., Surana, R.K., Danner, R.P., and Duda, J.L. (1997) Finite concentration inverse gas chromatography Diffusion and partition measurements. 

Kovat s retention index (p. 575) liquid-solid adsorption chromatography (p. 590) longitudinal diffusion (p. 560) loop injector (p. 584) mass spectrum (p. 571) mass transfer (p. 561) micellar electrokinetic capillary chromatography (p. 606) micelle (p. 606) mobile phase (p. 546) normal-phase chromatography (p. 580) on-column injection (p. 568) open tubular column (p. 564) packed column (p. 564) peak capacity (p. 554)... 

At first glance, the contents of Chap. 9 read like a catchall for unrelated topics. In it we examine the intrinsic viscosity of polymer solutions, the diffusion coefficient, the sedimentation coefficient, sedimentation equilibrium, and gel permeation chromatography. While all of these techniques can be related in one way or another to the molecular weight of the polymer, the more fundamental unifying principle which connects these topics is their common dependence on the spatial extension of the molecules. The radius of gyration is the parameter of interest in this context, and the intrinsic viscosity in particular can be interpreted to give a value for this important quantity. The experimental techniques discussed in Chap. 9 have been used extensively in the study of biopolymers. 

This chapter contains one of the more diverse assortments of topics of any chapter in the volume. In it we discuss the viscosity of polymer solutions, especially the intrinsic viscosity the diffusion and sedimentation behavior of polymers, including the equilibrium between the two and the analysis of polymers by gel permeation chromatography (GPC). At first glance these seem to be rather unrelated topics, but features they all share are a dependence on the spatial extension of the molecules in solution and applicability to molecular weight determination. 

Column Si. Size-exclusion chromatography columns are generally the largest column on a process scale. Separation is based strictly on diffusion rates of the molecules inside the gel particles. No proteins or other solutes are adsorbed or otherwise retained owing to adsorption, thus, significant dilution of the sample of volume can occur, particularly for small sample volumes. The volumetric capacity of this type of chromatography is determined by the concentration of the proteins for a given volume of the feed placed on the column. 

Fig. 5. Continuous process for producing phosphatidylcholine. 1, Lecithin 2, ethanol 3, blender 4, diffuser 5, thin-type evaporator 6, ethanol-insoluble fraction 7, heat exchanger 8, chromatography column (Si02) 9, prestream 10 and 12, phosphatidylcholine solution 11, circulating evaporator 13, dryer ...

Assay Methods. The primary assay for the streptovaricins is the microbiological assay using the agar diffusion method or a turbidimetric procedure (60). The streptovaricins can also be identified by paper (60,88) or thin-layer chromatography (3). 

Several properties of the filler are important to the compounder (279). Properties that are frequentiy reported by fumed sihca manufacturers include the acidity of the filler, nitrogen adsorption, oil absorption, and particle size distribution (280,281). The adsorption techniques provide a measure of the surface area of the filler, whereas oil absorption is an indication of the stmcture of the filler (282). Measurement of the sdanol concentration is critical, and some techniques that are commonly used in the industry to estimate this parameter are the methyl red absorption and methanol wettabihty (273,274,277) tests. Other techniques include various spectroscopies, such as diffuse reflectance infrared spectroscopy (drift), inverse gas chromatography (igc), photoacoustic ir, nmr, Raman, and surface forces apparatus (277,283—290). 

FIG. 16 36 Dimensionless time-distance plot for the displacement chromatography of a binary mixture. The darker lines indicate self-sharpening boundaries and the thinner lines diffuse boundaries. Circled numerals indicate the root number. Concentration profiles are shown at intermediate dimensionless column lengths = 0.43 and = 0.765. The profiles remain unchanged for longer column lengths. 

Azobenzene [103-33-3] M 182.2, m 68", pK 2.48. Ordinary azobenzene is nearly all in the transform. It is partly converted into the cw-form on exposure to light [for isolation see Hartley J Chem Soc 633 1938, and for spectra of cis- and /ran5-azobenzenes, see Winkel and Siebert Chem Ber 74B 6707947]. trans-Azobenzene is obtained by chromatography on alumina using 1 4 benzene/heptane or pet ether, and crystd from EtOH (after refluxing for several hours) or hexane. All operations should be carried out in diffuse red light or in the dark. 

Lab method using porous polymer adsorption tube and thermal desorption with gas chromatography Lab method using porous polymer diffusive samplers with thermal desorption and gas chromatography Lab method using pumped acid-coated filters, desorption and liquid chromatography... 

Eormaldehyde in air Lab method using diffusive sampler, solvent desorption and high performance liquid chromatography 78... 

Lab method using porous polymer diffusive samplers, thermal desorption and gas chromatography 43... 

Lab method using charcoal diffusive samplers, solvent desorption and gas chromatography (using Drager ORSA monitor) 64... 

Benzene m air (porous polymer diffusion samplers, thermal desoiption and gas chromatography) Quartz in respirable airborne dusts (X-ray diffraction)... 

The value of (q) takes into account the precise shape of the pool of stationary phase for a uniform liquid film as in a GC capillary column, q = 2/3. Diffusion in rod shaped and sphere shaped bodies (e.g., paper chromatography and LC) gives q=l/2 and 2/15, respectively [2]. 

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