Acid ethoxylates cleavage

The determination of alkyl chain distribution of alcohol ether sulfates can be most easily performed by gas chromatography after cleavage of the sulfated ethoxy moiety with hydri-odic acid. This procedure is similar to that described under the analysis of ethoxylated nonionic surfactants. The alkyl iodides from cleavage may also be determined by HPLC (72). An alternative approach requires the decomposition of the sulfate and ethoxy groups with the mixed anhydrides of paratoluenesulfonic and acetic acid, followed by GC determination of the alcohol acetates (73). 

Henning, M., H. Locke, R. lanniello. Identification of hydrophobes in normal alcohol ethoxylates by hydriodic acid cleavage and reversed-phase HPLC analysis with UV detection. 7. Liq. Chromatogn, 1989, 72,757-770. 

GC methods are summarized in Tables 2 and 3. Sulfates of alcohols and ethoxylated alcohols are readily decomposed by acid hydrolysis to yield the free alcohols or ethoxylated alcohols. The trimethylsilyl derivatives of these are easily analyzed by gas chromatography (24). Derivatization of the alcohols may be omitted if they have reasonable volatility (25). Alternatively, the surfactant may be decomposed by hydriodic acid, giving alkyl iodide derivatives of the starting alcohols for characterization by gas chromatography (26). Hydrolysis can be combined in the same step with derivatization. Reaction of alkyl sulfates with silylating agents such as BSTFA/1% TMCS results in cleavage of the sulfate and formation of the trimethylsilyl ethers of the alcohols (27). GC or GC-MS analysis will... 

C ()-Ci8 alkyl amine ethoxylates determination of alkyl chain distribution Cleavage/derivatization with acetic anhydride/p-toluene-sulfonic acid 15% Free Fatty Acid Phase (poly(ethylene glycol) nitroterephthalate) on Uniport B, 3 mm x 1 m 235 - C TC 53... 

If the identity of the nonionic surfactant is known and it can be separated from interfering compounds, it may be determined by the method of HI cleavage (72). The material is refluxed with hydriodic acid in the absence of oxygen, leading to decomposition of the ethoxylate chain and the formation of free iodine, which is titrated in the usual manner with sodium thiosulfate. 

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