Adsorption on glass

Such analytes require carefully chosen extraction conditions in terms of pH, solvent composition and technique. Also, these analytes tend to become lost by adsorption on (glass) surfaces or undergo conjugation so that a chemical or enzymatic deconjugation step may be required. Often only the use of radiotracers... 

Hence, one can see that the energy of y change activation may be interpreted as heat of singlet-oxygen adsorption on glass. 

It is pointless to dilute CaCl2 to 10-6 M for standardizing an ion-selective electrode. At this low concentration, Ca2+ will be lost by adsorption on glass or reaction with impurities. 

The most general feature of the adsorption behavior of metal ions at solid-aqueous solution interfaces is the abrupt rise in adsorption over a narrow pH range. This has been illustrated, for example, for manganese adsorption on glass (2), cobalt on hydrous ferric oxide (8), manganese on hydrous manganese oxide (12), protactinium on glass (14), and... 

Fig. 23. Brash and ten Hove s results on the adsorption of three plasma proteins from diluted plasma as a function of total plasma concentration. Up adsorption on glass showing a maximum adsorption of fibrinogen at about 1% plasma Down adsorption on polyethylene plasma was diluted with isotonic Tris, pH 7.35. Adsorption time was 5 minutes (reprinted from Ref.1031)...

Selective adsorption on glass Ammonium sulfate fractionation Ammonium sulfate fractionation Ethanol precipitation Sonic disintegration Selective adsorption on cellulose phosphate CM-cellulose chromatography Acetone precipitation Ammonium sulfate fractionation Ethanol precipitation Selective adsorption on cellulose phosphate Ammonium sulfate fractionation Lysozyme and trypsin digestion Ammonium sulfate fractionation DEAE-cellulose chromatography Ammonium sulfate fractionation... 

Figure 6. Langmuir kinetic model fitting of Cl adsorption on glass (a) fractional coverage as a function of time and solution concentration, (b) equilibrium coverage as a function of concentration, and (c) check of fitting of equation 2 by the correlation of the fitted exponential constant and concentration.

FIGURE 8. Polyncr adsorption on glass Fibers, as Function oF acid/base concepti, ... 

Flow-Through Column Measurements. All apparatus in contact with the wastewater solution was made of plastic (either Teflon or polypropylene) to avoid adsorption on glass walls. A Teflon cylinder with bed dimensions of 56 mm long x 25... 

Air (occupational) Adsorption on glass fiber filter and Florisil hexane desorption GC/ECD 0.0006 mg/m for 50 L sample No data NIOSH 1984a (method 5503)... 

In addition, the rate of extraction may be different for the same analyte depending on the nature of the sample matrix. Obviously, as in all analyses the problem of controlling the level of contamination is crucial. It is essential to use the highest purity solvents (as any subsequent concentration may also concentrate the impurity as well as the analyte of interest) and to wash all associated glassware thoroughly. As well as contamination, care should also be exercised to minimize analyte losses due to adsorption on glass containers. A typical procedure for LLE is described in Figure 8.3. 

Relative activity of FX adsorbed As FX reactivity with the synthetic substrate was lower than that of thrombin, 40 yl of 0.4 units/ml FX solution was added to 2 ml of a 0.05 M phosphate buffer containing 0.05 M KCl at pH 7.4. The FX adsorption on glass beads was investigated using almost the same methods as those adopted for thrombin, except that specific activities of FX in the remaining solution and on beads were evaluated as values relative to a FX solution. 

Static Adsorption of Plasma Proteins on Glass. Initial studies of the interaction of proteins with artificial surfaces concerned the highly simplified situation of static adsorption on glass from solutions of purified radiolabeled human plasma proteins. Albumin was chosen as a major plasma protein known for its non thrombogenic properties (5>6). Fibrinogen and fibronectin, on the contrary, are major proteins of plasma which enhance platelet and cellular adhesion (4.5.7.23-25). 

Figure 7. Adsorption on glass from various mixtures of albumin and fibrinogen. Reproduced with permission from Ref. 7-Copyright 1976, Pergamon Press, Inc.

Figure 8. Adsorption on glass from the ternary system fibrinogen-albumin-I G, concentrations 0.09 1.20 and 0.36 mg ml respectively Buffer 0.05 M Tris, pH 7.35.

Adsorption on glass fiber filters is simple, inexpensive, and popular. The large internal surface of the filters adsorbs membrane vesicles via weak electrostatic and hydrophobic interactions. Bigger vesicles (mitochondriae, synaptosomes) are also filtered mechanically (pore size of glass fiber filters 1 to 3 pm 0 mitochondriae 1 pm). Molecules in solution largely... 

Bakaev et al. [77] employed a similar approach to study CO2 adsorption on glass surfaces. Their results confirm that CO2 molecule is sensitive to the structure of the surface while Ar does not show this characteristic. In another paper Bakeva et al. [78] studied CO2 adsorption on glass fibers in a wide temperature range. Employing the classical volumetric technique they have determined the adsorption isotherms and also calculated the isosteric heats of adsorption. They have also analyzed their data in terms of the independent adsorption sites model [74,79,80]. The most important equation of this model is... 

Simulation of alkali ion adsorption on glass surfaces and their diffusion into subsurface layers is of importance because it helps us understand the effects of contaminants on the properties of optical fibers. Garofalini and Zirl,2oi for example, studied the adsorption and diffusion of K and Li on vitreous silica. These simulation studies revealed that potassium ions diffuse over the surfiice and adsorb preferentially on the nonbridging oxygen, whereas... 

That the effect of dilution on catalase activity is in part due to adsorption of the enzyme on the surfaces of the reaction vessel was shown by Harkins et al. in 1940 (171). Agner (personal communication) found that the addition of glass beads to dilute catalase removes part of the enzyme from the solution. Svendsen (338a) describes some quantitative measurements of catalase adsorption on glass surfaces in a recent publication. 

Research on the chemistry of transactinide elements was resumed in the mid 1980s at Berkeley by the first study of element 105 in aqueous solution [123]. The a-particle emitter, 35-s Db, produced by the " Bk( 0,5n) reaction, served as a probe. The investigated chemical topic was the adsorption on glass in very strong nitric acid, a characteristic property of tantalum and niobium. Dubnium was found to share this property. Due to the very low production rate of Db, some 800 manually performed experiments were required to obtain a statistically satisfying result based on 24 a-decay events altogether. This example showed that automated, computer-controlled online procedures were needed for a broad exploration of the open territory. 

Figure 4. (A) Assembly of I2nm nanc article on glass monitored by optical extinction. Spectrum was collected at 5,10, IS, 30,60,120, and lOSOminutes. (B) Kinetics of gold nanopaiticle adsorption on glass measured by the change in Ext° as a function of time.

Investigations may be carried out on the tracer level, where solutions are handled in ordinary-sized laboratory equipment, but where the substance studied is present in extremely low concentrations. Concentrations of the radioactive species of the order of 10 m or much less are not unusual in tracer work with radioactive nuclides. A much larger amount of a suitably chosen non-radioactive host or carrier is subjected to chemical manipulation, and the behavior of the radioactive species (as monitored by its radioactivity) is determined relative to the carrier. Thus the solubility of an actinide compound can be judged by whether the radioactive ion is carried by a precipitate formed by the non-radioactive carrier. Interpretation of such studies is made difficult by the formation of radiocolloids, and by adsorption on glass surfaces or precipitates. Tracer studies provide information on the oxidation states of ions and complex-ion formation, and are used in the development of liquid-liquid solvent extraction and chromatographic separation procedures. Tracer techniques are not applicable to solid-state and spectroscopic studies. Despite the difficulties inherent in tracer experiments, these methods continue to be used with the heaviest actinide and transactinide elements, where only a few to a few score atoms may be available [11]. 

Figure 2.55. Aggregate size dependencies of epoxide ohgomer ED-5 on its concentration and temperature in toluene solution during adsorption on glass spheres.

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