Mixtures containing amphoteric surfactants

An unknown commercial detergent may contain some combination of anionic, nonionic, cationic, and possibly amphoteric surfactants, inorganic builders and fillers as weU as some minor additives. In general, the analytical scheme iacludes separation of nonsurfactant and inorganic components from the total mixture, classification of the surfactants, separation of iadividual surfactants, and quantitative determination (131). 

The possible procedures involving titration with SDS or BEC all depend on pH control, and are therefore not applicable to mixtures containing alkali-labile quats. It is better to assume that such mixtures will necessitate separation, and the guidelines given below assume that alkali-labile quats are absent, and that only one quat and one amphoteric are present, although the astute analyst will be able to work out schemes for some mixtures containing more than one surfactant of each class. 

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. 

Fire-extinguishing foams containing mixtures of a cationic, an amphoteric, and a nonionic fluorinated surfactant [150] have been claimed to spread rapidly on hydrocarbon surfaces. 

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