Surface-active chemical

Bonnet, C.F. " Treatment of Oil Sands with Surface-Active Chemicals," 1941 Mid-Year Meeting of the American Petro-Institute, Division of Production, Tulsa, May 22. See also Division of Production Transactions, Vol. 22MIIV] (1941). 

Cristoni S, Bernardi LR, Gerthoux P, Gonella E, MocareUi P. 2004. Surface-activated chemical ionization ion trap mass spectrometry in the analysis of amphetamines in diluted urine samples. Rapid Commun Mass Spectrom 18 1847. 

Chemical flotation aids. There are a variety of surface active chemicals that can be used to improve flotation performance. 

Chapter 17. Estimating the Properties of Surface-Active Chemicals Johannes Tolls and Dick T.H.M. Sijm... 

Tolls, Johannes et al "Estimating the Properties of Surface-Active Chemicals"... 

C. Hopf, W. Jacob, A. von Keudell Ion-induced surface activation, chemical sputtering, and hydrogen release during plasma-assisted hydrocarbon film growth. J. Appl. Phys. (2005) in print... 

Foams form where surface-active chemicals or "surfactants" are present. Surfactants also are called amphipathic agents and are characterized by the presence of both hydrophilic and hydrophobic functional groups (7). Surface-active agents that may be present in natural waters include fulvic and humic acids, collectively termed humic substances, (2,3), fatty acids and lipids (4), and proteins (5), and all have been identified as contributing surfactants in the few characterization studies that have been conducted on natural foams in freshwater environments (5-70) and marine surface layers (77-76). 

Recently, a LC/MS method to determine OTA in wine and grape extracts by using Surface-Activated-Chemical-Ionization and multistage fragmentation mass spectrometry (LC/SACI-MS3), was proposed (Flamini et al., 2007). SACI is an ionization source developed to analyze medium-high polar compounds in a wide range of m/z ratios (100-4000 Da). This device, used in determination of compounds such as... 

Flamini, R., Dalla Vedova, A., De Rosso, M. and Panighel, A. (2007) A New Sensitive and Selective Method for Analysis of Ochratoxin A in Grape and Wine by direct liquid chromatography/surface activated chemical ionization-tandem mass spectrometry, Rapid Commun. Mass Spectrom. 21(22), 3737-3742. 

Cristoni, S., Rossi Bernardi, L., Guidugli, F., Tubaro, M., and Traldi, P. (2005). The role of different phenomena in surface-activate chemical ionization (SACI) performance, J. Mass Spectrom., 40,1550-1557. 

Figure 8.3. The SACI/MS2 and MS3 fragmentation patterns of OTA and ZAN [M+H]+ ions. (Reprinted from Rapid Communications in Mass Spectrometry 21, Flamini et al., A new sensitive and selective method for analysis of och-ratoxin A in grape and wine by direct liquid chromatography/surface activated chemical ionization-tandem mass spectrometry, p. 3738, Copyright 2007, with permission from John Wiley Sons, Ltd.)...

Sensitivity 45 Sieve-based-device 39 Single-focusing mass spectrometers 49 Surface-Activated Chemical Ionisation 35... 

Role of Adsorbed Surfactant Layer. Foams, irrespective of the nature of liquid and gas involved, require a third component for stabilization of thin films (lamellae) of the liquid. In the familiar case of aqueous soap films, this third component is the soap, a surface-active chemical that adsorbs at the gas—liquid interface and lowers the surface tension of water. The two effects, adsorption at the liquid surface and the depression of surface tension, are intimately linked and occur concomitantly. The adsorption is defined as the excess moles of solute per unit area of the liquid surface. In a binary system, this surface excess can be directly related to the lowering of surface tension by Gibbs adsorption equation ... 

The role of surface elasticity provided by the adsorbed layer of surfactant molecules remains the same in aqueous and nonpolar foams, however, its relative importance and effectiveness is different. A major difference lies in the magnitude of surface tension gradient that can be generated by the surface-active chemicals. Because the surface tension of pure water is very high (73 mN/m), many surfactants can lower the surface tension by more than 50 mN/m. The surface tension of nonpolar solvents is typically around 25 to 30 mN/m. Therefore, even the best surfactants can only provide a much smaller reduction in its value. 

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