Mixtures containing amphoteric

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. 

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 production of steel begins when iron ore is fed into a blast furnace (Fig. 16.39). The furnace, which is approximately 40 m high, is continuously replenished from the top with a mixture of ore, coke, and limestone. Each kilogram of iron produced requires about 1.75 kg of ore, 0.75 kg of coke, and 0.25 kg of limestone. The limestone, which is primarily calcium carbonate, undergoes thermal decomposition to calcium oxide (lime) and carbon dioxide. The calcium oxide, which contains the Lewis base O2", helps to remove the acidic (nonmetal oxide) and amphoteric impurities from the ore ... 

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. 

ION RETARDATION. A process hused on amphoteric (hifunclionalt ion-exchangc resins containing both anion and cation adsorption sites. These siies will associate with mohile anions and cations in solution and thus remove both kinds of ions from solutions. These ions may be eluted bv rinsing with water. This process can make elean separations of ionic-nonitmic mixtures It has also been suggested fur demineralization of salt solutions. 

The protein molecule has free carboxyl and amino groups. Therefore it exhibits amphoteric properties. A number of color reactions have been developed for proteins to determine the presence of specific amino acids. The following are among the most important Millon s reaction. This reaction consists in the development of a red coloration when a substance containing a monohydroxyben-zene group is heated with a mixture of mercuric nitrate and nitrite (MUlon s reagent). Proteins giving this reaction contain tyrosine. 

Separation of Amphiprotic Species In isoelectric. separation of amphiprotic species, the separation is performed in a buffer mixture that continuously varic.s in pH along its length. This pH gradient is prepared from a mixture of several different ampholytes in an aqueous solution. Ampholytes arc amphoteric compounds usually containing carboxylic and amino groups. Ampholyte mixtures having different pH ranges can be prepared or arc available from several commercial sources. 

Like the constituent amino acids, proteins and peptides are amphoteric and exist in the solid state as zwitterions (10.40) since they contain terminal amino and carboxylate groups. In solution the state of ionisation is pH dependent. At very acid pH the molecules are in form (10.40a), at very alkaline pH they are in form (10.40c), and at intermediate pH values mixtures of (a), (b) and (c) are present. 

The pH gradient is established with the aid of a mixture of low-molecular weight amphoteric substances (ampholytes). Such mixtures are manufactured by LKB (Ampholines), Pharmacia (Pharmalytes), etc. These ampholytes are synthetic zwitterionic species that differ from each other in their pl-values, and a set of ampholytes covers more or less uniform pi ranges from 2-3 to 10-11. They contain amino groups (basic groups) and carboxylic groups as well as acidic ones (Ampholines, Pharmalytes). 

As in previous chapters, this chapter deals with the analysis of cationics and amphoterics either alone, as raw materials or as fractions isolated by ion exchange or otherwise, or in formulated products. Fractions isolated by ion exchange are likely to contain other materials, analogously with anionics. Amines, ethoxylated amines and amine oxides are included in this chapter because they are bases and capable of a cationic function. They are retained as cations by ion-exchange columns and do not appear in the nonionic fraction of separated mixtures, they can be titrated with acids and, in acid solution, with sodium dodecyl sulphate, provided the ethylene oxide chains of ethoxylates are not too long. 

---