Ester ethoxylates titration

The ethoxylated ester concentration is obtained by difference. During the titration for assay, a value, in milliequivalents per gram, was obtained for total amine ethoxylate and ester ethoxylate. This value is corrected for the ethoxylated amine content and equivalent... 

Highly concentrated ether carboxylic acids with a low degree of ethoxylation even at room temperature can give an esterification reaction with the non-converted nonionic, especially with the fatty alcohol, to several percentage points. The result may be that a too low value is found for the ether carboxylate content. This mistake in analysis can be avoided by saponification of the formed ester [238]. Two hundred to 300 mg matter and ca 100 mg NaOH were weighed in a 50-ml Erlenmeyer glass, heated with 20 ml ethanol under reflux, and after cooling supplied with water to 100 ml. Afterward a two-phase titration was carried out. 

A polyvinyl acetate latex prepared by semi-continuous polymerization at 55° using a polymethacrylic acid-nonylphenol-poly-ethoxylate phosphate ester emulsifier and sodium persulfate-sodium formaldehyde sulfoxylate initiator (23). The latex was cleaned by ion exchange and serum replacement using both Nuclepore and Pellicon membranes, and the cleaned latex and serum fractions were analyzed by conductometric titration. In addition, the dried films were extracted with water and organic solvents, and the extracts were analyzed by infrared spectroscopy and thermo-gravimetric analysis. 

The determination of active agent is complicated by the presence of various impurities in the commercial product ethoxylated ethanolamine, ethoxylated ester, polyethylene glycol, fatty acid. The nonaqueous titration is rapid, but requires knowledge of the equivalent weight of the surfactant. This makes the method unsuitable for the analysis of unknown materials unless further characterization is performed. 

Dissolve a sample containing about 0.5 meq total base in 50 mL acetic anhydride. Titrate potentiometrically, using a glass combination electrode, with 0.1 M HCIO4 in acetic acid. Titrate to the second, weak break. This value corresponds to the sum of the ethoxylated amide, ethoxylated amine, and ethoxylated ester. Dissolve a second portion of the sample, about five times as much as titrated above, in glacial acetic acid. Titrate potentiometrically with 0.1 M HCIO4 in acetic acid. This titration gives the sum of the ethoxylated amine and ethoxylated ester. Calculation ... 

Ethoxylated esters of fatty acids and sorbitol, sucrose, and glycerin are widely used in food and pharmaceuticals, and their analysis is performed according to compendial methods. The specified methods are generally those listed in Section II of this chapter, as well as modifications of the above procedures applied to unethoxylated esters. Like other polyethoxy compounds, these can be determined in aqueous solution by titration with tetraphe-nylborate ion as described in Chapter 16 (124). 

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