Alkylamido betaines

Therefore, a C13-AE, a cationic (quaternary ammonium) surfactant (quat), an amphoteric Ci2-alkylamido betaine, and the non-ionic fatty acid diethanol amide (FADA) as presented with their FIA-MS spectra in Fig. 2.5.12(a)-(d) were analysed as pure blends and as mixtures always obtained from two blends in FIA-MS multiple ion detection mode (MID). Mixtures as well as pure blends contained identical concentrations of surfactant homologues. For AE quantitation the mass traces of all A m/z 44 equally spaced homologues (m/z 306-966) of the C13-AE were recorded. The cationic (quaternary ammonium) surfactant, the amphoteric Ci2-alkylamido betaine, and the non-ionic FADA were quantified recording the mass traces at m/z 214 and 228, or 184, 212, 240, 268, 285, 296, 313, 324 and 341, or 232,260, 288, 316 and 344, respectively. 

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. 

If N-containing surfactants, e.g. quats, alkylamido betaine or FADA, were ionised together with AE a depression was expected for AE compounds because of the proton affinity of the amino nitrogen... 

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. 

An improved specificity was observed when FIA-MS-MS in product or parent ion mode was used to perform quantification of the surfactants in the methanolic mixtures. The ions selected for quantitation in product or parent ion mode were C13-AE m/z 71, 85, 99, 113, and 127 from alkyl chain together with 89, 133, and 177 from PEG chain generated from parent ions m/z 394, 526, 658, 790 and 922 alkylbenzyl dimethyl ammonium quat m/z 91 and 58 generated from parent ion m/z 214 FADA m/z 88, 106 and 227 generated from parent ions m/z 232, 260, 288, 316, 344 and 372 while the alkylamido betaine was quantified generating the parent ion m/z 343 obtained from product ion at m/z 240. 

The production of alkylamido betaines is usually accomplished in two steps. The first involves the formation of an alkylamidopropyldimethylamine, which is then followed by a carboxymethylation step to form the final betaine (Figure 15.6). 

Alkylamido betaines are usually supplied as 30% aqueous solutions, containing several by-products, which may effect the physical properties or the toxicological profile of the betaine. Formerly, CAPB contained approximately 3% of the amidoamine because of an incomplete reaction. The amidoamine has some advantages, contributing to viscosity and providing some sub-stantivity to hair and skin. The tertiary amine is an irritant and sensitization is suspected to be related to the level of the tertiary amine (10) or the dimethyl aminoamine (11). The content of amidoamine in modem... 

Amphoteric surfactants Alkyl betaine, alkylamido betaine, alkylamphoacetate <10... 

The amphoteric surfactants are relatively expensive products compared to anionic surfactants. Thus, it is not surprising that they are primarily being utilized at low concentrations in cosmetic formulations. A review of 438 shampoos of the U.S. market reveals that appreciable quantities, for example, >5% of alkylamido betaines and imidazolinium surfactants were found in only 8.7% and 13.5%, respectively, of the investigated shampoos. Alkyl betaines were found in a limited number of cases, whereas sulfo betaines were not found in this stndy [4,5]. Since these studies were made, the market has focused on mild products. The change in the U.S. market from bar to liquid soaps has increased the use of alkylamidopropyl betaines. 

Alkylamido betaines are the most common of the betaine types. They have become the most important type of secondary surfactants, especially cocamidopropyl betaine (CAPB) [22], which can also... 

Koshti and Naik (2003) Sodium monochloroacetate Alkylamido betaine LC... 

AES type surfactants were examined qualitatively in the ESI—FLAMS mode but, from the result, the presence of AES seemed to be doubtful. After a LC separation presenting the TIC in the form of a contour plot the identification of AES surfactants in parallel with an amphoteric surfactant mixture of alkylamido propyl betaine type was possible [50]. 

In general, betaines are compatible with anionic surfactants. The simpler alkyl betaines are found to be less compatible with alkyl sulfates than the alkylamido-propyl betaines, especially when the concentration of betaine is about one half that of the lauryl sulfate [1], This incompatibility is related to the pH of the system as well as the nature of the anionic species present. 

Figure 15.7. Flowability of aqueous solutions of alkylamido-propyl betaines (at 25°C)...

---