Ionic surfactants, mass

Figure 1.13 Schematic representation of the water/oil interfacial tension = 0.50, the interfacial tension (Xat, decreases from 50 mN m 1 to values as low as 1 0-4 mN m 1. After having crossed the monomeric solubility 70 of the surfactant in the water- and oil-rich phase, 70, where the microemulsion phase (c) exist in form of a lens (right). (From Ref. [26], reprinted with permission of Elsevier.)...

Fig, 3. Cole-Cole plot characteristic for the dielectric relaxation exhibited by microemulsions using non-ionic surfactants. Mass proportion of surfactant in the undecane phase 12%. Mass fraction of water in the system p = 0.093. Temperature T = 36°C. 

Recent studies, including the use of Microtox and ToxAlert test kits [55,56], were carried out for the determination of the toxicity of some non-ionic surfactants and other compounds (aromatic hydrocarbons, endocrine disruptors) before implementation on raw and treated wastewater, followed by the identification and quantification of polar organic cytotoxic substances for samples with more than 20% inhibition. Furthermore, the study of their contribution to the total toxicity was obtained using sequential solid-phase extraction (SSPE) before liquid chromatography-mass spectrometry (LC-MS) detection. This combined procedure allows one to focus only on samples containing toxic substances. 

V. Non-ionic surfactants Flow injection analysis—mass... 

Fig. 2.6.6. APCI-LC-MS-MS(+) (CID) daughter ion mass spectrum of [M + NH4]+ ion at m/z 678 generated from Cig-SPE of foam sample. Compound could be identified as non-ionic surfactant NPEO (CgHi9-C6H4-0-(CH2-CH2-0)m-H) (inset)... 

SPECTROMETRY—V. NON-IONIC SURFACTANTS FLOW INJECTION ANALYSIS—MASS SPECTROMETRY AND LIQUID CHROMATOGRAPHY—MASS SPECTROMETRY OF ORGANOSILICONE SURFACTANTS... 

ATMOSPHERIC PRESSURE IONISATION MASS SPECTROMETRY—VI. NON-IONIC SURFACTANTS LC-MS OF OTHER NON-IONIC SURFACTANTS... 

Fig. 2.9.5. APCI-FIA-MS-MS(-I-) (CID) product ion mass spectrum of selected [M + NH4]+ parent ion (m/z 476) of non-ionic surfactant metabolite identified as PEG homologue (general formula H0-(CH2-CH2-0)X-H) fragmentation behaviour under CID presented in the inset [35].

Fig. 2.9.13. APCI-FIA-MS-MS(+) (CID) product ion mass spectrum of unknown parent ion with rn/z 598, identified as non-ionic surfactant of AP type (CnH2n+i-0-(CH(CH3)-CH2-0) ,-H) (inset) fragmentation scheme under CID conditions [24]. 

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]. 

Because of their excellent biodegradability, alkylether carboxylates (AECs) (general structure CnH2 +i-0-(CH2-CH2-0)n-CH2-C00 ) are used more frequently today in households for cleaning purposes. From the structure shown in Fig. 2.11.11, mass spectra as observed in the ionisation of AES or non-ionic surfactants of the ethoxy type with equally spaced signals (Am/z 44) can be expected [22],... 

For sensitive quantification in LC-MS analysis of non-ionic surfactants, selection of suitable masses for ion monitoring is important. The nonionic surfactants easily form adducts with alkaline and other impurities present in, e.g. solvents. This may result in highly complicated mass spectra, such as shown in Fig. 4.3.1(A) (obtained with an atmospheric pressure chemical ionisation (APCI) interface) and Fig. 4.3.2 (obtained with an ESI interface). 

Calculated concentrations, using (4.9), for the various components, surfactant monomers, counter-ions and micelles, for the case of CTAB micellization (with a cmc of 0.9mM), is shown in Figure 4.5. Clearly, the micelle concentration increases rapidly at the cmc, which explains the sharp transition in surfactant solution properties referred to earlier. It is also interesting to note that the law of mass action (in the form of equation 4.9) predicts an increase in counterion (Br ions) concentration and a decrease in free monomer concentration above the cmc. It has been proposed that for ionic surfactants, a useful definition of the cmc would be... 

LC-MS uses different types of soft chemical ionization that produces molecular ions and no fragmentation pattern. In MS/MS instruments the molecular ions can be fragmented by collision with a gas for example, He. This fragmentation can be used for identification of a compound. No mass spectral libraries exist for LC-MS hence identification of unknown compounds is more time-consuming than for GC-MS. For known compounds LC-MS is a very sensitive and specific method, using LC-MS/MS systems the analytical performance can be increased even more. LC-MS analysis is especially suitable for non-volatile POMs such as non-ionic surfactants in house dust samples (Clausen et al., 2003). 

The first of these theories applies the law of mass action to the equilibrium between unassociated molecules or ions and micelles, as illustrated by the following simplified calculation for the micellisation of non-ionic surfactants. If c is the stoichiometric concentration of the solution, x is the fraction of monomer units aggregated and m is the number of monomer units per micelle,... 

Aqueous Solutions The transition temperature above which a non-ionic surfactant or wax loses some of its water solubility and becomes ineffective as a surfactant. The originally transparent surfactant solution becomes cloudy because of the separation of a surfactant-rich phase. Cloud points are typically reported on the basis of tests for a specified surfactant concentration such as 1 mass%. See also Coacervation. 

Otsuki and Shiraishi [3] used reversed phase absorption liquid chromatography and field desorption mass spectrometry to determine polyoxyethylene alkylphenyl ether non ionic surfactants in water. In the separation of polyoxyethylene octylphenyl, nonylphenyl and dodecylphenyl ethers by gradient elution with a holding process by holding the... 

Stephanou [38] identified non ionic surfactants in non saline water by gas chromatography coupled with chemical ionisation mass spectrometry. Tertiary octylphenol and lauryl alcohol ethoxylates were qualitatively detected using their chemical ionisation mass spectra and the results used to compare the chemical ionisation and electron impact mass spectrometry techniques. 

Microscopic foam films have been used to study the steric interaction between two liquid/gas interfaces [130]. Two ABA triblock copolymers of the Synperonic PE series were employed P85 and F108. These commercial non-ionic surfactant were used as obtained from ICI Surfactants, Witton, UK. Blocks A are hydrophilic polyethylene oxide (PEO) chains, while block B is a hydrophobic polypropylene oxide (PPO) chain. The molecular masses and average EO contents are known from the manufacturer and yield approximate chemical formulae (Table 3.3). Data about the surface tension of electrolyte-free aqueous copolymer solutions can be seen in Fig. 3.31 [130]. It was additionally checked that NaCl (up to 510 2 mol dm 3) had no influence on these values. 

The characterization of water-soluble components in slurries is one use of SPME with mixed solid-liquid samples. In one application, dried homogenized solid samples (10 mg of sewage sludge or sediment) were slurried in 4 ml of H,0 saturated with NaCl and adjusted to pH 2 with HCl for extraction for 1-15 h, which was followed by desorption into 4 1 methanol/ethanol over 2 min. The extracted compounds were either injected into a liquid chromatograph or fed directly via an electrospray ionization interface to a mass spectrometer with 1 s miz scans from 50-700 or selected-ion monitoring. The major components extracted included phthalates, fatty acids, non-ionic surfactants, chlorinated phenols and carbohydrate derivatives [235]. 

A pronounced influence of the pH on the adsorption of ionic surfactants requires special attention to be paid when carrying out the experiments. For example, if the experimental results obtained in different measurements are to be compared or correlate with one another, the same solid-to-solution mass ratio has to be maintained. 

Applications of FAB have been succesfully performed in the characterization of a wide range of compounds (dyes, surfactants, polymers...) but little attention has been devoted to the capabilities of this technique to solve environmental concerns, such as organic pollutants identification in water. The widespread use of surfactants in the environment has required the emplo yment of both sensitive and specific methods for their determination at trace levels. GC/MS and HPLC procedures has been used for the determination of anionic (LAB s) and non ionic surfactants (NPEO) in water (1-4). Levsen et al (5) identified cationic and anionic sirrfactants in surface water by combined field desorption/ collisionally activated decomposition mass spectrometry (FD/CAD), whereas FAB mass spectrometry has been used for the characterization of pine industrial surfactants (6-8). 

Stacking the isothermal Gibbs triangles on top of each other results in a phase prism (see Fig. 1.3(a)), which represents the temperature-dependent phase behaviour of ternary water-oil-non-ionic surfactant systems. As discussed above, non-ionic surfactants mainly dissolve in the aqueous phase at low temperatures (2). Increasing the temperature one observes that this surfactant-rich water phase splits into two phases (a) and (c) at the temperature T of the lower critical endpoint cepp, i.e. the three-phase body appears. Subsequently, the lower water-rich phase (a) moves towards the water corner, while the surfactant-rich middle phase (c) moves towards the oil corner of the phase prism. At the temperature Tu of the upper critical endpoint cepa a surfactant-rich oil phase is formed by the combination of the two phases (c) and (b) and the three-phase body disappears. Each point in such a phase prism is unambiguously defined by the temperature T and two composition variables. It has proved useful [6] to choose the mass fraction of the oil in the... 

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