Surfactants blends

Studies on mechanisms are described by Balzer [192]. In the case of anionics the residual oil in the injection zone is removed via displacement into the adjacent reservoirs ether carboxylates show their good adaptation to differences in temperature and salinity. Further it was found from interfacial tension measurements, adsorption and retention studies, and flooding tests that use of surfactant blends based on ether carboxylates and alkylbenzensulfonates resulted... 

Modem oil spill-dispersant formulations are concentrated blends of surface-active agents (surfactants) in a solvent carrier system. Surfactants are effective for lowering the interfacial tension of the oil slick and promoting and stabilizing oil-in-water dispersions. The solvent system has two key functions (1) to reduce the viscosity of the surfactant blend to allow efficient dispersant application and (2) to promote mixing and diffusion of the surfactant blend into the oil film [601]. 

Surfactant blends of interest will exhibit clouding phenomena in aqueous solutions undergoing a phase transition from a one phase system to a two phase system at a discrete and characteristic temperature, referred to as the Cloud Point (CP). This value indicates the temperature at which sufficient dehydration of the oxyethylene portion of the surfactant molecule has occurred and this results in its "displacement" from solution. The addition of lyotropic salts will depress the CP, presumably due to the promotion of localised ordering of water molecules near the hydrophilic sheath of the surfactant molecule (8). Furthermore, the addition of different oils to surfactant solutions can induce either an elevation or a depression of the recorded CP and can be used to qualitatively predict the PIT (8x9). 

Favourable phase inversion conditions, as monitored by conductivity, were established for all surfactant blends in contact with alkanes. 

Surface wave, 17 422. See also S-wave Surfactant adsorption, 24 119, 133-144 at the air/liquid and liquid/liquid interfaces, 24 133-138 approaches for treating, 24 134 measurement of, 24 139 at the solid/liquid interface, 24 138-144 Surfactant blends, in oil displacement efficiency, 13 628-629 Surfactant-defoamers surface tension, <5 244t Surfactant-enhanced alkaline flooding,... 

As a consequence, for unequivocal identification of the constituents of complex mixtures found in surfactant blends and also in the analyses of surfactants and their metabolites in environmental samples, MS and tandem mass spectrometry (MS-MS) have proved to be more advantageous and are discussed thoroughly in Chapter 2. To optimise the output of reliable results and to save manpower and time certain procedures in sample preconcentration, clean-up and separation prior to MS examinations are inevitable. These are discussed in the present book in more detail in Chapter 3. 

These observations obtained from the application of different API techniques are determinative for qualitative and quantitative FIA results in the analysis of non-ionic and ionic surfactants. Therefore, both ionic surfactant types, anionic and cationic surfactant blends, besides a non-ionic AE surfactant blend were examined, recording their FIA-MS and MS-MS spectra from the blends before the spectra were generated from the mixture of all blends. The results, which show considerable variation, will be presented and discussed as follows. 

These results obtained from the analyses of industrial blends proved that the identification of the constituents of the different surfactant blends in the FIA-MS and MS-MS mode can be performed successfully in a time-saving manner only using the product ion scan carried out in mixture analysis mode. The applicability of positive ionisation either using FIA-MS for screening and MS-MS for the identification of these surfactants was evaluated after the blends examined before were mixed resulting in a complex surfactant mixture (cf. Fig. 2.5.7(a)). Identification of selected mixture constituents known to belong to the different blends used for mixture composition was performed by applying the whole spectrum of analytical techniques provided by MS-MS such as product ion, parent ion and/or neutral loss scans. 

Fig. 2.5.7. (a) APCI-FIA-MS(+) screening recording an artificial formulation mixed from surfactant blends as presented in Figs. 2.5.3 (AES), 2.5.5 (AE) and 2.5.6 (polyglycol amine blend). Product ion spectra of selected parent ions m/z 380, 556 and 670 of surfactant formulation as in (a) obtained by APCI-FIA-MS-MS(+). 

By summing up the results of qualitative analysis of surfactant blends and formulations achieved by FIA-MS and MS-MS in comparison with LC-MS and MS-MS applied for identification, considerable differences could be observed and should be taken into consideration prior to analysis ... 

To recognise ion suppression reactions, the AE blend was mixed together either (Fig. 2.5.13(a) and (b)) with the cationic quaternary ammonium surfactant, (c, d) the alkylamido betaine compound, or (e, f) the non-ionic FADA, respectively. Then the homologues of the pure blends and the constituents of the mixtures were quantified as presented in Fig. 2.5.13. Ionisation of their methanolic solutions was performed by APCI(+) in FIA-MS mode. The concentrations of the surfactants in the mixtures were identical with the surfactant concentrations of the blends in the methanolic solutions. Repeated injections of the pure AE blend (A 0-4.0 min), the selected compounds in the form of pure blends (B 4.0—8.8 min) and their mixtures (C 8.8— 14.0 min) were ionised and compounds were recorded in MID mode. For recognition and documentation of interferences, the results obtained were plotted as selected mass traces of AE blend (A b, d, f) and as selected mass traces of surfactant blends (B a, c, e). The comparison of signal heights (B vs. C and A vs. C) provides the information if a suppression or promotion has taken place and the areas under the signals allow semi-quantitative estimations of these effects. In this way the ionisation efficiencies for the pure blends and for the mixture of blends that had been determined by selected ion mass trace analysis as reproduced in Fig. 2.5.13, could be compared and estimated quite easily. 

Fig. 2.5.12. APCI-FIA-MS(+) overview spectra of industrial surfactant blends used as pure blends or mixtures in the examination of ionisation interferences, (a) C13-AE, (b) cationic (alkyl benzyl dimethyl ammonium quat) surfactant, (c) amphoteric C12-alkylamido betaine, and (d) non-ionic FADA all recorded from methanolic solutions. 

Matrix assisted laser desorption ionisation (MALDI) and ESI-MS spectra of non-ionic surfactant blends of AE obtained after positive ionisation were compared [28]. Both the ionisation procedures, which produce [M + Na]+ ion clusters, were very useful for this purpose, but the ESI spectra generated were more complex, whereas MALDI ionisation led to simpler spectra that can be interpreted more easily [28]. 

Fig. 2.9.20. APCI-FIA-MS-MS(+) (CID) product ion mass spectrum of [M + NH4]+ parent ion of EO/PO surfactant blend (C H2 +i-0-(E0)x-(P0) v-H). Selected parent compound ion m/z 598 (inset) fragmentation scheme under CID conditions [24].

The homologues of the methylated non-ionic EO/PO surfactant blend were ionised as [M + NH4]+ ions. A mixture of these isomeric compounds, which could not be defined by their structure because separation was impossible, was ionised with its [M + NH4]+ ion at m/z 568. The mixture of different ions hidden behind this defined m/z ratio was submitted to fragmentation by the application of APCI—FIA—MS— MS(+). The product ion spectrum of the selected isomer as shown with its structure in Fig. 2.9.23 is presented together with the interpretation of the fragmentation behaviour of the isomer. One of the main difficulties that complicated the determination of the structure was that one EO unit in the ethoxylate chain in combination with an additional methylene group in the alkyl chain is equivalent to one PO unit in the ethoxylate chain (cf. table of structural combinations). The overview spectrum of the blend was complex because of this variation in homologues and isomers. The product ion spectrum was also complex, because product ions obtained by FIA from isomers with different EO/PO sequences could be observed complicating the spectrum. The statistical variations of the EO and PO units in the ethoxylate chain of the parent ions of isomers with m/z 568 under CID... 

Fig. 2.9.41. APCI-FIA-MS(+) overview spectrum of gemini surfactant blend Surfynol (2,4,7,9-tetramethy]-5-decyne-4,7-polyol) [16].

Fig. 2.9.44. ESI-FIA-MS(+) overview spectra of partly fluorinated non-ionic surfactant blend with the general formula C F2n+1-(CH2-CH2-0)m-H identical with CnF2n+1-CH CHa-O-CCHa-Cttj-O -j-H [16],... 

Fig. 2.9.46. (e) APCI-LC-MS(+) RIC of a mixture of standards containing a conventional AE blend (C12 and C14 homologues) and a fluorinated non-ionic surfactant blend (C F2 +i-(CH2-CH2-0)m-H n = 6 and 8) (a)-(d) selected mass traces of conventional C12 and C14 AE compounds or CB and Cg fluorinated AE compounds (h) APCI-LC-MS(-I-) RIC of wastewater sludge extract containing non-ionic fluorinated surfactants (f) and (g) selected mass traces of C6 and C8 fluorinated AE compounds extracted from sewage sludge. Gradient elution separated on perfluorinated RP-Cg column [52]. 

Fig. 2.11.25. ESI-FIA-MS( — ) spectrum of a partly fluorinated PFOS surfactant blend (CF3-(CF2)4-(CH2)8-S03H, mlz 461) containing by-product ions of CF3-(CF2)2-(CH2)8-S03H (mlz 361) and CFa-ICFah-fCHa -SOaH mlz 411) [61].

Fig. 2.12.4. FIA-APCI-MS-MS(+) CID product ion mass spectrum of selected [M]+ parent ion of cationic quat surfactant blend RR N (CH3)2X at mtz 304 characterised as alkyl di-methylbenzyl ammonium acetate fragmentation pattern presented in the... 

Fig. 2.12.6. Identification of esterquat compounds FIA-APCI-MS-MS(+) (CID) product ion mass spectrum of selected [M — RCO]+ base peak ion of cationic surfactant blend of di-hydrogenated tallowethyl hydroxyethyl ammonium methane sulfate type (mlz 692 general formula (R(C0)0CH2CH2)2-N (CH3)-CH2CH2(0H)CH30S03) fragmentation behaviour under CID...

Fig. 2.12.8. FIA-APCI-MS-MS(—) (CID) product ion mass spectrum of a selected [M — H] parent ion (mlz 583) of cationic fluorinated quaternary alkyl ammonium surfactant blend (general formula CnF2n+i- S02-NH-CH2-CH2-CH2-N (CH3)3 x ...

Cationic surfactant blends of quats were studied by FIA-ESI-MS(+). The general formula of the compounds was (R)nN (CH3)4 n with R = C12-C22. These compounds applied in products for personal... 

One of the major goals of these many investigations of lipids is, of course, a better understanding of the in - vivo behavior of membranes. Beyond studies of binary lipid mixtures, as mentioned above, a further step which is necessary is the incorporation of proteins into the layers. In many respects, this increase in the complexity of the bilayer systems resembles that encountered in the use of synthetic surfactants in "real - world" situations, where blends, rather than single, surfactants are used. Surfactant blends in aqueous solutions are often further modified in use by the solubilization of oily organic compounds, as in the cases of detergency or cosmetic formulation. 

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