Surfactants compounds

The calibration curve obtained for hydrogen peroxide exhibited a detection limit of 30 pmol and ranged over three decades at least. These performances compared well with those previously obtained in non-micellar media54. The presence of surfactant compounds in the ECL measurement buffer appeared thus to have little effect on the H2O2 ECL sensor performances. In optimized conditions, the determination of free cholesterol could be performed with a detection limit of 0.6 nmol and a calibration curve ranging over two decades at least. 

The experiments on emulsion cumene oxidation with AIBN as initiator proved that oxidation proceeds via the chain mechanism inside hydrocarbon drops [17]. The presence of an aqueous phase and surfactants compounds does not change the rate constants of chain propagation and termination the ratio (fcp(2fct)-1/2 = const in homogeneous and emulsion oxidation (see Chapter 2). Experiments on emulsion cumene oxidation with cumyl hydroperoxide as the single initiator evidenced that the main reason for acceleration of emulsion oxidation versus homogeneous oxidation is the rapid decomposition of hydroperoxide on the surface of the hydrocarbon and water drops. Therefore, the increase in the aqueous phase and introduction of surfactants accelerate cumene oxidation. 

In the analyses of polar anthropogenic surfactant compounds, the application of substance-specific MS-detection in combination with... 

Fig. 2.9.15. APCI-FIA-MS-MSMS-MS(+) (CID) product ion mass spectrum of selected [M + NH4]+ parent ion (m/z 266) compound was identified as metabolite (aldehyde compound) of degradation product of non-ionic surfactant compound PPG (general formula H0-(CH(CH3)-CH2-0)x-CH(CH3)-CH0 ( = 3) fragmentation behaviour under CID presented in the inset [22].

A special type of surfactant compounds, so-called H-active compounds consisting of condensation products of EO/PO polymers with com-... 

Fig. 2.9.23. APCI-FIA-MS-MS(+) (CID) product ion mass spectrum of [M + NH4]+ ion of methylated EO/PO surfactant compound (CnH2n+i0-(CH2-CH(CH3)-0) y-(CH2-CH2-0) l.-CH3) with m/z 568 (inset) fragmentation scheme under CID ot conditions [24],...

The MS analysis using ESI was applied for the determination of an unknown surfactant compound contained in an extract of a shampoo formulation [44]. MS leading to sequential product ions helped to identify the constituents. The MS4 experiments together with other spectral observations confirmed the hypothesis that the unknown compound was a N-( 2-aminoethyl) fatty acid amide with the general formula R-C(0)-NH(CH2-CH2-N)R/R,/. An authentic sample of the proposed laury ampho mono acetate (LAMA) (R = -CH2-CH2-OH and R" = -CH2-CH2-COOH) that was available led to the same [M + H]+ parent ion at m/z 345. The fragmentation that could be observed under ESI-FIA-MS-MS(+) conditions resulted in an intensive examination of amide surfactants. However, only two of them—lauryl diethanol amide ([M + H]+ m/z 288), a non-ionic surfactant and laurylamido-(3-propyl betaine ([M + H]+ m/z 343)—... 

Fig. 2.9.33. ESI-FIA-MS-MS(+) (CID) product ion mass spectrum of parent ion with m/z 370 of industrial blend of unsaturated FADA surfactant compound could be identified as diethanolamide derivative of oleic acid (CH3-C7H14-CH=CH-C7H14-C(0)-N(CH2-CH2-OH)2) (inset) fragmentation scheme observed under CID conditions [16].

NPEO-SO4 is one of the rare anionic surfactant compounds on which aerobic biodegradation monitoring has been performed, where metabolites could be observed by API-MS. Using FIA-MS, however, differentiation of precursor compounds and metabolites was impossible. Both compounds showed the same molar masses but could be recognised because of their quite different RTs in RP-LC [15]. MS CID performed by trap confirmed a fragmentation behaviour of the metabolite quite different from precursor NPEO-SO4 compounds, whose structure is not yet clear. 

Partly fluorinated or perfluorinated sulfonic and carboxylic acids are compounds with excellent surface activity combined with an extreme stability against chemical or physico-chemical attacks as also described for non-ionic fluorine containing surfactant compounds. The anionic surfactants are shown with their structural formulae in Fig. 2.11.24(1)—(III). A selected ESI-FIA-MS(-) spectrum of a partly fluorinated surfactant (CF3-(CF2)4-(CH2)8-S03H, m/z 461) is presented in Fig. 2.11.25. The FIA spectrum also contains ions of the by-products CF3-(CF2)2-(CH2)8-S03H (m/z 361) and CF3-(CF2)3-(CH2)8-S03H (m/z 411). 

Fluorinated phosphinic and phosphonic acid derivatives Perfluoro derivatives of alkyl phosphonic acid CnF2n+1-P(0)(0H)2 and alkyl phosphinic acid CnF2n+i(CmF2m+1)-P(0)0H (n = m or n m) shown with their general structural formulae in Fig. 2.11.29(1) and (II) were examined by negative ESI- and APCI-FIA-MS. These anionic surfactant compounds contained perfluoro alkyl chains [2,22,25]. By analogy with their behaviour in the TSI-FIA-MS(—) process [25], the phosphonic acid formed [M — H] ions at m/z 399 and 499... 

The determination of alkyltrimethyl ammonium surfactant compounds with the general formula RN (CH3)3 X- were performed using continuous flow (CF) FAB (CF-FAB) and ESI. Dodecyl-, tetradecyl- and... 

Fig. 2.12.15. FIA-APCI-MS-MS(+) (CID) product ion mass spectrum of cationic surfactant compound (m/z 538) fatty acid polyglycol amine type observed in the Saale river, Germany (general formula R—N H((CH2—CH2—OH)x)—(CH2—CH2—OH)y X fragmentation behaviour of [M]+ parent ion at m/z 538 under CID conditions is presented...

An interesting historic parallel (91) can be drawn to van t Hoffs proposal of the tetrahedrd geometry for groups bound to a tetra-valent carbon atom because its original appearance was also in the form of an obscure pamphlet in Dutch (Utrecht, 1874) however, van t Hoffs work was quickly translated into French (1875) and German (1876) for publication in vehicles having considerably wider circulation. In Zeelen s case, only the synthetic aspects of his dissertation were subsequently published in the journal literature (92). However, the later paper does provide a cautionary note that the surfactant compounds employed in the film balance studies may not have been optically pure because racemization during their synthesis was possible. 

Heat can be used to break some emulsions Changing the pH of the water can often break an emulsion The presence of acid-forming and sulfate-reducing microorganisms may enhance the formation of emulsions treat the fuel with a microbiocide Formulate fuels with a demulsifier to inhibit emulsion formation Ensure that surfactant compounds and additives... 

The solubility of the sodium salt of (meta-sulfonatophenyl)diphenylphos-phine, TPPMS in water is approximately 12 g/L at room temperature.5 It dissolves slightly in cold ethanol, but is soluble at elevated temperatures. It is virtually insoluble in acetone and aliphatic, aromatic, or chlorinated hydrocarbons, but is soluble at room temperature in tetrahydrofuran. The compound crystallizes with two waters of crystallizations however, the anhydrous form can also be obtained.3 Dry TPPMS is stable to air but is oxidized rapidly when wet, especially in basic aqueous solutions. It is a highly surfactant compound and forms aggregates and micelles in neutral aqueous... 

This technique is a variant of CZE. A cationic or anionic surfactant compound, such as sodium dodecylsulphate, is added to the mobile phase to form charged micelles. These small spherical species, whose core is essentially immiscible with the solution, trap neutral compounds efficiently by hydrophylic/hydrophobic affinity interactions (Fig. 8.7). Using this type of electrophoresis, optical purity analysis can be conducted by adding cyclodextrins instead of micelles to the electrolyte. This is useful for separating molecules that are not otherwise separable. Under such conditions, the enantiomers form inclusion complexes of different stability with cyclodextrin (cf. 3.6). 

A number of experimental techniques by measurements of physical properties (interfacial tension, surface tension, osmotic pressure, conductivity, density change) applicable in aqueous systems suffer frequently from insufficient sensitivity at low CMC values in hydrocarbon solvents. Some surfactants in hydrocarbon solvents do not give an identifiable CMC the conventional properties of the hydrocarbon solvent solutions of surfactant compounds can be interpreted as a continuous aggregation from which the apparent aggregation number can be calculated. Other, quite successful, techniques (light scattering, solubilization, fluorescence indicator) were applied to a number of CMCs, e.g., alkylammonium salts, carboxylates, sulfonates and sodium bis(2-ethylhexyl)succinate (AOT) in hydrocarbon solvents, see Table 3.1 (Eicke, 1980 Kertes, 1977 Kertes and Gutman, 1976 Luisi and Straub, 1984 Preston, 1948). 

Alkylbenzene sulfonates (R-C6H5-S03Na) are important surfactant compounds used in laundry detergents. Alkylbenzenes (made by the Friedel-Crafts alkylation of benzene using linear olefin molecules that have about twelve carbon atoms) are sulfonated, and the sulfonic acids are then neutralized with NaOH. 

Micelles are molecular aggregates formed in solutions of surface-active agents (surfactants compounds that orient at an interface such as between oil and water) (McAulifFe, 1980). Micelles may contain up to 100 or more surfactant molecules with a nonpolar (hydrophobic) end on the inside and a polar (hydrophilic) end on the outside. In 1959, Baker first advanced the concept of solubilization of hydrocarbons in (soap) micelles as a possible primary migration mechanism. The possible role of soaps, i.e. salts of organic acids, in primary migration was supported by Cordell (1973). The concept was considered attractive because it also explains how the practically water-insoluble hydrocarbons can solubilize in groundwater at relatively low temperatures. However, the likelihood of micellar solution as an effective primary migration mechanism has been seriously questioned by many authors (for instance Price, 1976 Hunt, 1979 Tissot and Welte, 1984). The main problems associated with micellar solution are ... 

Ferrocene was functionalized at the 1,1 -positions by a sugar moiety (1-amino-l-deoxy-D-sorbitol) and a long alkyl chain 44 in order to obtain lyotropic properties. The substituents, in particular the sugar framework, were selected in view of successful investigations performed with organic-type amphiphilic carbohydrate surfactants. Compound 44 showed both thermotropic and lyotropic mesophases. In the bulk, a SmA phase formed from 98 to 137 °C. When 44 was mixed with an excess of water, a fluid phase was obtained. For the thermotropic SmA phase, a r/-layer spacing... 

---